Zugzwang [tsuːktsvaŋ] is a situation found in game play wherein the player with the advantage whose turn it is to move ends up with a significantly worse position following any move made. A player is said to be in zugzwang when he must move but any possible move will drastically worsen his position.

The term is also used in combinatorial game theory, where it means that the outcome of the game is altered from a win to a loss, but used less dramatically in games such as chess. Putting the opponent in zugzwang is a common tactic to win in modern grandmaster play, and in many instances, essential in order to make a win possible.