Polyamines of 97 strains (60 species) belonging to 18 genera of the family Enterobacteriaceae were determined by high performance liquid chromatographic analysis. In addition to putrescine and cadavarine, diaminopropane was widely distributed in Enterobacteriaceae and almost ubiquitously within Enterobacter, Pantoea, Erwinia, Leminorella, Proteus, Leclercia, Morganella, Klebsiella, Hafnia, Rahnella, Serratia, and Tatumella species and sporadically within Citrobacter, Escherichia, Moellerella, Providencia, Yokenella, and Yersinia species. Histamine was detected in some cultures of Proteus and Morganella. Agmatine was sporadically spread. Heterogeneity in the occurrence of spermidine was observed within the spermidine-containing cultures. Distribution profiles of 18 genera. Acetylated spermidine was found concomitantly in the spermidine-containing cultures. Distribution profiles of diaminopropane, spermidine, and acetylspermidine in Enterobacteriaceae can serve as a chemotaxonomic marker to distinguish this family from other taxa of the gamma subclass of the class Proteobacteria.