In 1983, the vernacular name Enteric Group 77 was coined for a group of strains that had been referred to our laboratory as "possible Vibrio cholerae except for gas production." By DNA-DNA hybridization (hydroxyapatite, 32P), 8 of 10 strains of Enteric Group 77 were very highly related to the labeled strain 1169-83 (74 to 100% at 60 degrees C and 75 to 100% at 75 degrees C; percent divergence, 0.0 to 2.5). Type strains of six other Aeromonas species were 45 to 66% related (60 degrees C) to strain 1169-83, but type strains of 27 Vibrio species were only 2 to 6% related. The name Aeromonas veronii is proposed for the highly related group of nine strains formerly known as Enteric Group 77. The type strain is designated as ATCC 35604 (CDC 1169-83). Strains of A. veronii grew well at 36 degrees C and had positive reactions at this temperature for indole, methyl red, Voges-Proskauer, citrate, lysine and ornithine decarboxylases, DNase, lipase, and motility; the strains had negative reactions for arginine decarboxylase, H2S, urea, and malonate. The following sugars were fermented: D-glucose (acid and gas), cellobiose (seven of nine strains), D-galactose, maltose, D-mannitol, D-mannose, alpha-methyl-D-glucoside (eight of nine strains), salicin, sucrose, and trehalose. The following sugars were not fermented: adonitol, L-arabinose, D-arabitol, dulcitol, erythritol, myo-inositol, lactose, raffinose, L-rhamnose, D-sorbitol, and D-xylose. The positive ornithine decarboxylase reaction differentiates A. veronii from other Aeromonas species. The antibiogram of A. veronii is typical of other Aeromonas strains (resistance to ampicillin and carbenicillin and susceptibility to most other agents). A. veronii strains were isolated from three clinical sources: respiratory secretions of four victims of drowning or near drowning in fresh water (probably not clinically significant); infected wounds of two patients previously exposed to fresh water (unknown clinical significance); and stools from three patients with diarrhea (probably clinically significant).