Anti-submarine warfare is a term referring to warfare directed against submarines. This involves the use of submarines, aircraft, and surface ships (commonly destroyers), to locate, track, and then either damage or destroy submarines, port facilities, production facilities, and supply routes.

Anti-submarine warfare also involves communication interception, decryption, and disinformation.

Since the introduction of submarines capable of carrying ballistic missiles, great efforts have been made to counter their threat. Nevertheless, successful anti-submarine warfare is as much a matter of luck as of science.

Sonar used in such operations is often of "mid-frequency". Such sonar has been argued to be a cause of whale beaching.

For a discussion of shipboard anti-submarine weapons and their history see ASW weapons.

See also: ASW Operations section in Modern Naval tactics