The 1981 American League Division Series (ALDS), the opening round of the 1981 American League playoffs, began on Tuesday, October 6, and ended on Sunday, October 11. The Division Series were approved by team owners on August 6 in response to the 1981 Major League Baseball strike, which caused the cancellation of roughly one-third of the regular season between June 12 and August 9; by the time play was resumed, it was decided that the best approach was to have the first-half leaders automatically qualify for postseason play, and allow all the teams to begin the second half with a clean slate.

The American League East is one of Major League Baseball's six divisions. MLB consists of an East, Central, and West division for each of its two 15-team leagues, the American League (AL) and National League (NL). This division was created before the start of the 1969 season along with the American League West division. Before that time, each league consisted of 10 teams without any divisions.