This study describes the production of a solid-phase assay (test strip/dipstick test) for putrescine and cadaverine in tuna based on the coupling of an amine oxidase to a peroxidase/dye system. The assay was linear to 75 microM in phosphate buffer, and the minimum detectable concentration was 0.5 microM (< 0.1 ppm), corresponding to 0.01 mg% in spiked extracts. Intra- and interassay precisions were < 20%. Test strips were stable at 4 degrees C for at least 12 months. Lysine, ornithine, and histidine did not react with the assay, and histamine reacted only minimally. Sixteen fish samples were tested by test strip and the standard AOAC protocol, and results were in good agreement.