An investigation was carried out to compare the clinical characteristics of infectious bronchitis virus strains in broiler chickens to have a basis for diagnosis of disease. The broiler chickens that suffered from respiratory problems in Soc Trang Province (10 samples from each flock) were surveyed for symptoms and gross lesions, and result swere combined with further testing by RTPCR (Reverse transcription polymerase chain reaction). The results showed that 60.0% of samples were positive to infectious bronchitis virus, in which, 50.0% and 33.3% of positive samples belonged to types 4/91 (793B) and M41 (Massachusetts), respectively, and the remaining positive samples (16.7%) belonged to LX4 (QX). This demonstrated that the infectious bronchitis virus was geneti cally diverse. Clinical characteristics of Massachusetts strains were mainly found in the respiratory tract, including tracheal rales, when breathing, sneezing, dyspnea, nasal discharge, sinusitis, conjunctivitis, tracheal petechial hemorrhage with exudate mucus, pulmonary hemorrhage and congestion, airsacculitis. Meanwhile, the 793B and QX IBV strains not only affected the same respiratory organs but also induced kidney damage (presented as pale swollen kidneys), watery diarrhea and sometimes urate deposition in the ureters. Therefore, the virus caused many different diseases, and these characteristics need to be used as the basis for the initial diagnosis of avian infectious bronchitis disease.