A new test combination for presumptive phenospecies identification of mesophilic aeromonads by testing for suicidal activity in conjunction with esculin hydrolysis and gas production from glucose was evaluated. Of 40 clinical isolates of Aeromonas tested statically at 30 degrees C, seven were identified as Aeromonas hydrophilia (non-suicidal, aerogenic, esculin positive), eight as Aeromonas sobria (suicide variable, mostly aerogenic, esculin negative), and 25 as Aeromonas caviae (suicidal, anaerogenic, esculin positive). The results corresponded exactly to those obtained with the conventional biochemical tests. The test combination was rapid and simple to perform.