1990 American League Championship Series

DatesOctober 6–10MVPDave Stewart (Oakland)UmpiresRich Garcia(crew chief)
John Hirschbeck
Jim Evans
Terry Cooney
Vic Voltaggio
Larry McCoyBroadcastTelevisionCBSTV announcersDick Stockton and Jim KaatRadioCBSRadio announcersJim Hunter and Johnny Bench

The 1990 American League Championship Series was a best-of-seven series in Major League Baseball's 1990 postseason that matched the East Division champion Boston Red Sox against the West Division champion Oakland Athletics. For the second time in three years, the Athletics swept the Red Sox four games to none. The sweep was capped by a Roger Clemens ejection in Game 4 for arguing balls and strikes. The Athletics would go on to lose to the Cincinnati Reds in the 1990 World Series in a four-game sweep.

This was the last pennant ever won by the Athletics during their time in Oakland, as the team would move to Las Vegas.