Histamine contents in 10 species of marine fish collected from retail markets in Cochin were estimated along with their bacterial profile in general and content of histidine decarboxylating bacteria in particular. The study reveals that none of the fish samples surveyed contained histamine above 1.3 mg/100 gm fish which is much below the recommended level as per U.S.F.D.A. specification, even though the histidine decarboxylating bacterial counts were of the order of 10⁴ per gm of fish muscle.