A quick, accurate method for the determination of histamine in tuna rish has been developed. Histamine is recovered from fish extracts by ion exchange chromatography, derivatized with o-phthalaldehyde and measured by the intensity of the resulting fluorophore. From filtered crude extracts, 12 samples can be determined per man hour including reconditioning of the ion exchange columns. Recoveries of histamine added at levels of 5 and 30 mg/lOOg to extracts from acceptable quality fish ranged from 98-103%. Recoveries of 94-101% were demonstrated for histamine added at levels of 30 and 100 mg/lOOg to extracts of decomposed fish. Multiple analyses agree within 0.5 mg at a level of 100 mg/lOOg and within 5.0 mg at a level of 100 mg%. The method is at least as accurate as the official AOAC calorimetric procedure and less prone to error by virtue of its simplicity.