Drafted in the third round of the 1966 entry draft, 17th overall, by the Montreal Canadiens, Drouin played for their junior team, the Montreal Junior Canadiens of the Ontario Hockey Association, in the 1966-67 season, playing in 47 games and scoring a sparkling 32 goals and 36 assists. The following two seasons Drouin turned pro with the Houston Apollos of the Central Hockey League playing some with the Canadiens in spot duty. The 1970 season found Drouin in the minors again, this time for the powerhouse Montreal Voyageurs, where he dominated with 106 points in 65 games, winning the Dudley "Red" Garrett Memorial Award for rookie of the year and leading the American Hockey League in scoring.
With no place for him in the powerful Montreal lineup, Drouin was traded to the Minnesota North Stars for the 1971 season, and he exploded, leading the North Stars in scoring with 68 points and adding 12 points in 12 games in the playoffs. Drouin would be a mainstay of the North Stars for four and a half seasons in all, his best season coming in 1973, when he scored career highs of 27 goals and 73 points.
His production fell thereafter, and he was traded in midseason in 1975 to the New York Islanders. The trade rejuvenated Drouin, and he was an effective two-way player for three seasons with the up-and-coming Isles.
Drouin's production sharply dropped in 1978, and disgruntled with his declining role with the Islanders, sat out the following season in order to become a free agent. He signed with the Winnipeg Jets thereafter, but his starring days long behind him, retired early in the 1981 season.
|1966–67||Montreal Junior Canadiens||OHA||47||32||36||68||64||--||--||--||--||--|
|1970–71||Minnesota North Stars||NHL||75||16||52||68||49||12||5||7||12||10|
|1971–72||Minnesota North Stars||NHL||63||13||43||56||31||7||4||4||8||6|
|1972–73||Minnesota North Stars||NHL||78||27||46||73||61||6||1||3||4||0|
|1973–74||Minnesota North Stars||NHL||65||19||24||43||30||-||-||-||-||-|
|1974–75||Minnesota North Stars||NHL||38||4||18||22||16||-||-||-||-||-|
|1974–75||New York Islanders||NHL||40||14||18||32||6||17||6||12||18||6|
|1975–76||New York Islanders||NHL||76||21||41||62||58||13||6||9||15||0|
|1976–77||New York Islanders||NHL||78||24||29||53||27||12||5||6||11||6|
|1977–78||New York Islanders||NHL||56||8||17||22||12||5||0||0||0||5|