The following is the list of squads that took part in the men's water polo tournament at the 1956 Summer Olympics.
[2] Head coach: Great Britain entered an unknown number of players.
[4] Head coach: Béla Rajki Italy entered a squad of eleven players.
[5] Head coach: Mario Majoni Romania entered a squad of nine players.
[8] Head coach: The United States entered a squad of eleven players.