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A total of 364 bacterial isolates, obtained from spinach leaves, were assayed in a decarboxylase broth containing histidine, lysine, and ornithine to check their ability to produce biogenic amines, and then quantified by high-performance liquid chromatography. Among these isolates, 240 formed cadaverine, 208 formed putrescine, and 196 formed histamine, in widely varying amounts. They frequently produced more than one biogenic amine. Klebsiella pneumoniaesubsp. pneumoniaeand Morganella morganiiwere the main histamine producers, with mean values of 1,600 and 2,440 mg/liter, respectively, followed by Pantoeaspp. 3 (1,710 mg/liter) and Hafnia alvei(2,500 mg/liter). Enterobacter amnigenusand Enterobacter cloacaeproduced particularly high amounts of putrescine, with mean values of 2,340 and 2,890 mg/liter, respectively. The strongest cadaverine formation was shown by Serratia liquefaciens(3,300 mg/liter), Serratia marcescens(3,280 mg/liter), and Stenotrophomonas maltophilia(1,000 mg/liter).