Fermentation of glucose, nitrate reduction, nitrate respiration, nucleoside phosphotransferase, and pectolytic activity were tested on 132 strains of the genus Erwinia obtained from the culture collections. All the strains of Erw. Amylovora formed taxonomically homogeneous group, while the strains designated as Erw. Amylovora var. salicis were heterogeneous and belonged to various genera and species. The strains of Erw. Carotovora were taxonomically heterogeneous and some of them were members of the genera of Enterobacter and Serratia. The strains of Erw. herbicola were homogeneous as far as the characteristics tested were concerned. For a rapid differentiation of Erw. amylovora, Erw. arotovora, and Erw. herhicola, test of the characteristics mentioned above is considered to be useful.