In 1950 he moved to the USA, where he played in the big bands of Sonny Dunham, Jimmy Dorsey, and others. In New York he studied flute with Harold Bennett (of the Metropolitan Opera orchestra) and clarinet with Leon Russianoff (principal of the New York Philharmonic Orchestra). Koffman returned to Toronto in 1955, thereafter dividing his career between his jazz group and studio work.

He became the booking agent for George's Spaghetti House in 1956 (remaining in this capacity and appearing there roughly one week each month with his band, the Moe Koffman Quartet and later the Moe Koffman Quintet, until 1994). The Canadian and US success, in 1958, of his recording of his Swinging Shepherd Blues established his name as a flutist and at the same time helped to popularize that instrument in jazz. In the 1960s Koffman engaged in various experiments, none necessarily original - eg, playing two saxophones at once, employing electronics to amplify and modify the saxophone's sound, and incorporating elements of rock into jazz. These left Koffman straddling the pop and jazz worlds and brought him unusually wide exposure for a Canadian jazz musician, including appearances in the mid-1960s on NBC TV's 'Tonight Show.' He led his own big band as music director in 1974 for Global TV's Everything Goes.

In the 1970s, assisted by the producer-arranger Doug Riley, Koffman initiated and made several popular LPs of arrangements of music by Bach, Berlioz, Debussy, Gluck, Grieg, Mozart, and Vivaldi. Two of the albums, Moe Koffman Plays Bach and Vivaldi's Four Seasons, reached gold record status in Canada, 1971-2. The initiative was typical of Koffman's refusal to be pigeon-holed by jazz purists, preferring instead to record what he perceived his audiences wanted. Of his 10 LPs in the 1970s only three could be considered purely jazz recordings: Solar Explorations, Live at George's, and Museum Pieces. For Solar Explorations he commissioned works in honour of the planets from Ron Collier, Riley, Fred Stone, Don (W.) Thompson, and Rick Wilkins. Koffman himself wrote Neptune and Venus. Museum Pieces, co-produced by GRT and the Royal Ontario Museum (Toronto), comprised works by Koffman (Museum Pieces and Evolution Blues), Marty Morell, Riley, Thompson, and Wilkins, inspired by various aspects of museology. While The Magic Flute in 1985 and Music for the Night in 1991 returned Koffman to a pop instrumental settings, his Duke Street releases 1986-90 were consistently in a jazz vein and comprised original tunes, themes by his longtime pianist Bernie Senensky, and jazz standards. Other compositions for which Koffman was known include the opening and closing themes ('Curried Soul' and 'Koff Drops,' respectively) for CBC Radio's As It Happens.

Benefitting from the wide exposure received by his pop ventures, Koffman led one of the most successful jazz groups in Canada, a quartet or, latterly, quintet with the guitarist Ed Bickert as a longstanding member (see Discography for details of personnel changes). The group appeared at Expo 67, performed in 1975 at the Shaw Festival (in a Mozart program with Camerata), and travelled in 1979 to Art Park (Lewiston, NY) and the Monteray Jazz Festival. Although some jazz circles held Koffman's commercial endeavours in disdain, he and his quintet appeared at various festivals including the Montreal Jazz Festival and the Ontario Place Jazz Festival. His national itinerary, however, was based for the most part on 'community concert' series. Koffman also appeared with several orchestras, including the TS (with which he was a soloist in Lucio Agostini's Flute Concerto in 1975), the Hamilton Philharmonic, the Sudbury Symphony Orchestra, Orchestra London Canada, the Kitchener-Waterloo, Calgary, and Edmonton symphony orchestras.

In 1982, with a performance in Stratford, Ont, the Koffman quintet began an occasional association with the renowned US jazz trumpeter Dizzy Gillespie. A few concerts followed each year until 1990, including those at the NAC, PDA, and Art Park in 1983, on a Canadian tour in 1987, and at the Budapest Spring Festival in 1989. (Koffman in turn played with Gillespie's United Nations big band for concerts in 1988 at the du Maurier Downtown Jazz festival in Toronto and the FIJM.) In 1991 the Koffman quintet undertook a similar association with the vibraphonist Peter Appleyard for concerts in western Canada and the Maritimes. The quintet alone toured in Australia (1980), South America (twice in 1985), and Germany (1990), and made several appearances at US universities during the decade. After George's Spaghetti House, the quintet's main venue, closed in 1994, Koffman began to perform regularly at The Senator, but the quintet on the whole performed less often.

During his entire career, Koffman was active as a soloist. He toured and recorded as lead altoist and featured soloist with the Boss Brass,1972-2000. He took similar roles in jazz-oriented TV and studio orchestras led by Peter Appleyard, Guido Basso, Jimmy Dale, and Rob McConnell. His reputation as a sight-reader and a quick study led to his being in demand as a studio musician and for commercial jingles, and he was a flute and/or woodwind soloist on many pop recordings, and in premieres of chamber works by Doug Riley and Paul Hoffert. Koffman received a Juno nomination 1991 for instrumental artist of the year.

The wide range of Koffman's activities has been seen by some as evidence of an inquiring musical mind and by others as merely the exercise of a keen instinct for popular tastes. Peter Goddard (Toronto Star, 15 Jul 1972) noted Koffman's 'rare ability to bob buoyantly on the surface of whatever new wave comes along'. The same range, however, exhibited on Koffman's own recordings and in other studio assignments, attests to his technical skill and musicianship. As a flutist he married a pure, 'classical' tone to the breezy rhythmic and melodic freedom of jazz; as an alto saxophonist he remained faithful to the bebop tradition and demonstrated with the Boss Brass and Dizzy Gillespie his standing among Canada's most vivid stylists in that idiom.

Koffman received PRO Canada's Wm Harold Moon Award in 1981 and the Toronto Arts award for music in 1991. He was inducted into the Canadian Music Hall of Fame (1997), and named an Officer of the Order of Canada (1993). He was named Flutist of the Year by the Annual Jazz Report Awards for 1993 and 1994, as well as being honoured by SOCAN in 1993 for jazz songwriting.

In his final decade, Koffman continued to compose, and to perform as a soloist and with his quintet at clubs and festivals. Beginning in 1989 and through the following decade, he booked orchestral musicians for musicals presented by Garth Drabinsky's Live Entertainment Corporation, including such shows as Phantom of the Opera, Showboat, and Ragtime. He made his last recording, The Moe Koffman Project, in the summer of 1999 (released in 2000 as Universal 012159271-2). His last public performance was in June 2000 for the du Maurier Downtown Jazz Festival, in Toronto. At the time of his death, he was inducted (as an inaugural member) into Canada's Jazz and Blues Hall of Fame.

Writing in the Globe and Mail in March 2001, Mark Miller assessed Koffman's crossover contributions: 'Mr. Koffman made music according to the principle of moderation. The best of his jazz and jazz/classical crossover LPs and CDs combined cautious experimentation, expert musicianship, keen intelligence and good taste to light and breezy effect.'

Koffman's -son Herb (trumpeter, b New York 22 Apr 1955) studied with Don Johnson and Ted Moses and was a member during the 1980s of Manteca.

Hot and Cool Saxophone. Long trumpet, McConnell trombone, E. Karam bar saxophone, Bickert guitar, Curry double-bass, Rully drums. 1957. Jubilee 5311

The Shepherd Swings Again. Bickert guitar, Curry double-bass, Rully drums. 1958. Jubilee JLP-1074

Moe Koffman the Swinging Shepherd Plays for Teens. 1962. Ascot AS-16001

Tales of Koffman. Amadio piano, Bickert guitar, Britto double-bass, Rully drums. 1962. U Artists JS-14209

The Moe Koffman Quartet. Bickert guitar, Price double-bass, Rully drums. 1963. CTL CTLS-5029

Moe Koffman Quartet. Ayre organ, Binsted double-bass, Cree drums. 1967. CBC Expo 31/RCI 268

Moe Koffman Goes Electric. Ayre organ, Pirie guitar, Binsted double-bass and sitar, Cree drums. 1967. Jubilee JGS-8009

Turned on Moe Koffman. 1968. Jubilee JGS-8016

Moe's Curried Soul. Riley Keybds, Breau guitar, Young double-bass, Lewis drums. 1969. Revolver RLPS-502

Moe Koffman Plays Bach. Riley keybds, Edwards guitar, Thompson double-bass, Clarke drums. 1971. GRT 9230-1008

Vivaldi's Four Seasons. String orch, Riley keybds, Edwards guitar, Bush guitar, Thompson double-bass, Clarke drums, Craden percussion. 1972. 2-GRT 9230-1022

Master Sessions. Riley keybds, Thompson double-bass, Clarke drums. 1973. GRT 9230-1041

Solar Explorations. Orch including soloists Basso trumpet, Stone flhn, Riley el pno, Greenwich guitar, Thompson piano and double-bass, Homme double-bass and bass guitar, Clarke drums, Ranger drums, Craden percussion. 1974. 2-GRT 9230-1050

Best of Moe Koffman. (1975). GRT 9230-1053

Live at George's. Thompson electric piano and piano, Riley piano, Bickert guitar, Homme double-bass and (electric) bass guitar, Fuller drums. 1975. 2-GRT 9230-1005

Jungle Man. Mallory guitar, Mann guitar, Riley el pno, Szczesniak (electric) bass guitar, McLaren drums, Leonard percussion. 1976. GRT 9230-1066

Museum Pieces. Str orch, Riley keybds, Thompson keybds, Bickert guitar, Homme double-bass and (electric) bass guitar, Morell drums. 1977. GRT 9230-1072

Things Are Looking Up. Str orch, Thompson keybds, Mann guitar, Bickert guitar, Homme double-bass and (electric) bass guitar, Morell drums. 1978. GRT 9230-1078

Back to Bach. Riley keybds, Mann guitar, Szczesniak (electric) bass guitar, McLaren drums, Leonard drums. 1979. Anthem ANR-1-1023

Best of Moe Koffman, vol 1. (1983). Anthem ANR-1-639

Best of Moe Koffman, vol 2. (1983). Anthem ANR-1-643

The Magic Flute. (1985). PolyTel PTL-17002

One Moe Time. Senensky keybds, Bickert guitar, Overs, double-bass, Clarke drums. (1986). Duke Street DSR-31023

Moe-Mentum. Senensky keybds, Bickert guitar, Overs double-bass, Elmes drums. (1987). Duke Street DSR-31036

Oop-Pop-A-Da. Gillespie trumpet and voice, Senensky keybds, Bickert guitar, Overs double-bass, Elmes drums. (1988). Duke Street DSR-31048

Moe Koffman Quintet Plays. Senensky keybds, Bickert guitar, Collins double-bass, Elmes drums. (1990). Duke Street DSR-31060 (CD and cass)

Music for the Night: a tribute to Andrew Lloyd Weber. Riley arr, conductor, kybds. 1991. Duke Street DSR-31073 (CD and cass)

The Moe Koffman Collection. (1993). Duke Street Records DSRC 31089

Devil's Brew. (1996). Duke Street Records DSRSD 31100

See also discographies for Guido Basso, the Boss Brass, and the Orford Quartet. Further details of Koffman's recordings and of many studio assigments to 1980 are included in the Canadian Jazz Discography

Steward, Hartley. 'Back to Bach with the Swingin' Shepherd,' Canadian Magazine, 17 Mar 1973

McNamara, Helen. 'Koffman saw musical opportunities in Canada, returned to stay,' MSc, 276, Mar-Apr 1974

Batten, Jack. 'Jazz boss,' SatN, Oct 1980

Miller, Mark. 'He's a man of many hats,' Toronto Globe and Mail, 29 Apr 1987

Barris, Alex. 'The Mighty Moe,' The Jazz Record, Summer 1993

'Moe Koffman.' Contemporary Canadian Musicians, Issue One. (Toronto 1997)

Miller, Mark. 'A jazzman for all seasons,' Toronto Globe and Mail, 30 March 2001