This study describes a simple and rapid multiplex-PCR method to determine the ability to produce histamine, tyramine and putrescine by bacteria. The assay is an improved method based on an assay designed for lactic acid bacteria. This improved method includes a pair of primers based on sequences from histidine decarboxylases from Gram-negative bacteria. Under the optimised conditions, the assay yielded a 367-bp DNA fragment from histidine decarboxylases of Gram-positive bacteria, 534-bp fragment from histidine decarboxylases of Gram-negative bacteria, 924-bp from bacterial tyrosine decarboxylases, and 1446-bp fragment from bacterial ornithine decarboxylases. The method was successfully applied to several biogenic amine-producing bacterial strains, even when DNAs of several target organisms were included in the same reaction. This simple method could be easily incorporated in food control laboratories to detect potentially biogenic amine-producing bacteria in foods.