The study was conducted to develop a PCR and an improved PCR-RFLP analysis method for rapid species-identification of Aeromonas genospecies. The forward and reverse primers for PCR were designed from the complementary sequences of the 16S rDNA of all 15-recognized Aeromonas genospecies to amplify a 1206-bp PCR product. The PCR amplified the expected product from the DNA template of type or reference strains of all recognized Aeromonas genospecies as well as 106 Aeromonas strains, while no PCR product was obtained from any of the non-Aeromonas strains tested. The PCR-RFLP analysis using the restriction enzymes (Alul, Mbol, Pvull, Pstl and Narl) provided identification of almost all Aeromonas species. However, the Aeromonas sp. T8 group and A. caviae exhibited a similar RFLP pattern. Some selected biochemical tests were found to be helpful for differentiation of the two species.