- May 4 MLB Baltimore Orioles Gregg Olson sets relief pitcher record of 41 consecutive scoreless innings
- May 5 116th Kentucky Derby: Craig Perret aboard Unbridled wins in 2:02
- May 9 NHL Prince of Wales Conference Final: Boston Bruins beat Washington Capitals, 4 games to 0
- May 9 Sampdoria of Italy win 30th European Cup Winner's Cup against Anderlecht of Belgium 2-0 in Gothenburg
Baseball Trade
May 11 NY Yankees trade Dave Winfield to Angels for Mike Witt
- May 12 NHL Clarence Campbell Conference Final: Edmonton Oilers beat Chicago Blackhawks, 4 games to 2
Sports History
May 14 46th time opposing pitchers hit HR, Fernando Valenzuela (Dodgers)/Gross (Expos)
- May 15 Edmonton Oiler Petr Klima scores to defeat Boston Bruins in third overtime period, the longest Stanley Cup Finals game in history
Sports History
May 18 Cubs Ryne Sandberg ends 2nd baseman record 123 errorless game streak
Stanley Cup
May 18 Edmonton right wing Jari Kurri sets record for scoring in a Stanley Cup Finals game with 3 goals and 2 assists in 7-2 win at Boston Garden
Preakness Stakes
May 19 115th Preakness: Pat Day aboard Summer Squall wins in 1:53.6
Baseball Record
May 22 Andre Dawson receives a record 5 intentional walks in a game
Sports History
May 22 Deion Sanders becomes involved in a dispute with Chicago White Sox catcher Carlton Fisk, one of the most infamous incidents of Sanders' baseball career
Sports History
May 26 Philadelphia Phillies retire future Baseball Hall of Fame 3rd baseman Mike Schmidt's uniform #20
Baseball Record
May 29 Rickey Henderson steals record 893rd base, breaking Ty Cobb's record