The longest Major League baseball game ever played, time wise was played May 8, 1984 featuring the Milwaukee Brewers and the Chicago White Sox. The game went 25 innings and lasted a total of 8 hours and 6 minutes. The game begin at 7:30 PM and was stopped for the night after 1:00 AM due to a curfew with the game tied at 3 after 17 innings. The game was then resumed the next afternoon and went another 8 innings before Chicago finally won the game 7-6.
The longest game, innings wise, in MLB history was played May 1, 1920 between the Brooklyn Dodgers and the Boston Braves. The game ended due to darkness after 26 innings with the teams tied at 1-1.