The 1999 Major League Umpires Association mass resignation was a labor tactic used by 68 Major League Baseball (MLB) umpires, including 66 members of the Major League Umpires Association (MLUA), the official umpires union at the time. Unable to strike because they had a labor agreement in place at the time, 57 umpires formally resigned by orchestrated letters in an attempt to force negotiations with MLB for a new labor agreement. The American and National Leagues instead immediately hired new umpires and accepted 22 of the resignations. The union membership became fractured on the issue, and the umpires tried to rescind their resignations, but the MLUA was unsuccessful in retaining the jobs of the 22 umpires and the resignations were seen as final. The incident led to the decertification of the MLUA and the formation of a new union, the World Umpires Association (WUA), now the Major League Baseball Umpires Association.