As a result of those team changes, the league had a seven-team East Division and a four-team West Division. Consequently, the league did not have a balanced home and away schedule between conferences. West Division teams played each other four times each, twice each home and away, while playing the East Division teams twice, once each home and away. Eastern Division teams played other East Division teams three times, while playing the West Division teams twice, once each home and away.
The playoff format was also modified with eight teams (five from the East and three from the West) now qualifying for the post-season, as opposed to six in the previous years. The fifth place team from the East would cross over and play in the West Division playoff bracket. In addition, the playoff format was changed from an aggregate score system to a total points system. Teams would play a two-game series, with teams earning two points for a victory, one point for a draw, and zero points for a loss, regardless of the score. If the teams were tied on points (e.g. each team won a game, or both games were ties), then the first tiebreaker was the teams playing a thirty-minute mini-game. If the mini-game resolved nothing, then penalty kicks were used as the second tiebreaker. In the mini-game, each team named a new lineup, could include three more substitutes and re-activate any players who sat out of Game Two for caution accumulation. Game Two home teams, the higher seeds, had an advantage as they had their entire 22-man active list available while away teams often traveled with as few as 14 players for economic reasons. The playoff final remained a one-off match, as in previous years, hosted by the top seed, or team with the best league record, in 1990.
Summary
Vancouver won their third consecutive West Division title, while Toronto won their second East Division title in a row. Once again, Vancouver and Hamilton met in the finals for the third consecutive season, with Vancouver winning the title for the third time in a row.
The playoffs were conducted with a total points system. Teams earned two points for a win, one point for a draw, and zero points for a loss. The team with the most points following the two-game series advanced. If the teams were tied on points, they played a 30-minute mini-game for a bonus point, followed by a penalty shootout if the mini-game remained tied.
^Winnipeg protested the result of the original second leg due to the fielding of an ineligible player, Geoff Aunger (who should have been suspended due to yellow card accumulation and who scored the winning goal in extra time), that the league office failed to communicate to the teams involved or match officials. The CSL league office mandated a last minute replay of the second leg on Thursday, September 20, 1990 in Winnipeg
^Ormsby, Mary (September 13, 1990). "Explosive 86ers win playoff opener; Blizzard one down". Toronto Star. p. F10.
^Stinson, Dan (September 17, 1990). "Rocket coach says 86ers won't be denied third title". Vancouver Sun. p. 27.
^ abcBender, Jim (September 13, 1990). "Fury on Pitch". Winnipeg Sun. p. 47.
^"Vistas storm back to eliminate Fury". Winnipeg Sun. September 16, 1990. p. 55.
^Bender, Jim (September 21, 1990). "CSL joke gets a punchline". Winnipeg Sun. p. 45.
^Lovegrove, Don (September 13, 1990). "Supra loses playoff opener to Steelers". Montreal Gazette. p. C1.
^Phillips, Randy (September 16, 1990). "Supra's season ends abruptly; Punchless offence fails to match Fashanu's goal". Montreal Gazette. p. C1.
^Ormsby, Mary (September 14, 1990). "GM blasts 'spoiled' Blizzard for 'shameful' effort". Toronto Star. p. F6.
^Ormsby, Mary (September 17, 1990). "Blizzard bow out in shootout". Toronto Star. p. D3.
^Keating, Jack (September 23, 1990). "Vistas show flair in tie with 86ers". The Province. p. 9.
^Stinson, Dan (October 1, 1990). "86ers roar to CSL's title game". Vancouver Sun. p. 19.
^"Hopes for Kitchener sink in East". The Province. September 24, 1990. p. 34.
^"The Spirit was willing but Steelers weren't weak". Vancouver Sun. October 1, 1990. p. C3.
^"86ers romp to third CSL title". Nanaimo Daily News. October 9, 1990. p. 15.
^ abJose, Colin (2001). On-Side - 125 Years of Soccer in Ontario. Vaughan, Ontario: Ontario Soccer Association and Soccer Hall of Fame and Museum. pp. 130, 133.