If a game is tied at the end of the third period in the NHL playoffs, periods of 20 minutes are played until a goal is scored. This differs from the rules of overtime in the regular season, where only one 5-minute overtime period is played followed by a shootout if the score remains tied.
Teams take a 15-minute intermission before the start of each overtime period in the playoffs. They alternate ends for each period. The first team to score a goal wins the game.
In theory there can be unlimited overtime periods, but the longest an overtime has ever gone in NHL history is six periods. This happened in 1933 with the Toronto Maple Leafs defeating the Boston Bruins on a goal by Ken Doraty, and again in 1936 with the Detroit Red Wings defeating the Montreal Canadiens on a goal by Mud Bruneteau. The 1936 game is the longest in NHL history. Two games have gone five overtime periods: one between the Pittsburgh Penguins and the Philadelphia Flyers in 2000, with Philadelphia prevailing on a goal by Keith Primeau, and one between the Anaheim Ducks and the Dallas Stars in 2003, with Anaheim winning on a goal by Peter Sykora.