OBJECTIVE To discuss the diagnostic value of an ultrasonic assessing system for detecting the severity of hepatic fibrosis in patients with chronic hepatitis B (CHB). METHODS Ultrasonographic variables were analyzed in 110 CHB patients. An ultrasonic semi-quantitative scoring system using seven ultrasonic morphologic parameters, a Fisher discriminating function and three quantitative ultrasonic parameters was developed. The performance of these methods was also studied and compared. RESULTS The areas under the curve of the scoring system for different liver fibrosis stages were >or= S2: 0.946, >or= S3: 0.914, and S4: 0.915. The total score was well correlated with the histological stage of fibrosis (r=0.824, P < 0.001). There was a significant difference between the stages of fibrosis. The accuracy of the Fisher discriminating function for identifying three study endpoints was 76.5%, 78.2% and 67.3%. Combining the ultrasonic scoring system and the discriminating function, the specificity was 85%-90% and the accuracy was 77%-84%. CONCLUSION Our ultrasonic semi-quantitative scoring system is a noninvasive method for quantitating liver fibrosis. If it is used together with a discriminating function, the accuracy of diagnosing liver fibrosis can be significantly increased.