The 1971 American League Championship Series was a matchup between the East Division Champion Baltimore Orioles and the West Division Champion Oakland Athletics. The Orioles swept the A's in three games, despite the fact that each team had won 101 games. The Orioles won their third consecutive pennant in the process, but lost the 1971 World Series to the Pittsburgh Pirates. This was the first of ten ALCS series between 1971 and 1981 that featured either the Oakland Athletics or the Kansas City Royals. The only time neither team appeared in the ALCS during that period was in 1979.