The following is the list of squads that took part in the men's water polo tournament at the 1956 Summer Olympics.

Australia

Australia entered a squad of nine players. Head coach:

Great Britain

Great Britain entered an unknown number of players. They scored 25 goals but all scorers are unknown. Head coach:

Hungary

Hungary entered a squad of eleven players. They scored 26 goals but only twenty scorers are known. Head coach: Béla Rajki

Italy

Italy entered a squad of eleven players. They scored 17 goals but all scorers are unknown. Head coach: Mario Majoni

Romania

Romania entered a squad of nine players. They scored 26 goals but all scorers are unknown. Head coach: Balint Adalbert

Singapore

The following players represented Singapore.

Soviet Union

The Soviet Union entered a squad of eleven players. They scored 21 goals. Head coach:

United States

The United States entered a squad of eleven players. They scored 15 goals but only three scorers are known. Head coach: Neill Kohlhase (coach), Sam Greller (manager)

United Team of Germany

Germany entered a squad of eleven players. They scored 16 goals but all scorers are unknown. Head coach:

Yugoslavia

Yugoslavia entered a squad of eleven players. They scored 25 goals but all scorers are unknown. Head coach: File Bonačić