To investigate the relationship between the polymorphism of class II transactivator (CIITA) gene promoters and chronic hepatitis B (CHB).Genomic DNA was prepared from peripheral blood leukocytes. Promoters I, III and IV of gene were analyzed respectively with polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) in 65 patients with CHB, 26 patients with acute hepatitis B (AHB) and 85 normal controls.No abnormal migration was found in PCR-SSCP analysis of the three promoters in the three groups. Also, no sequential difference was observed at the three promoters among the CHB patients, AHB patients and normal controls.No polymorphism in promoters I, III and IV of CIITA gene exists in CHB patients, ABH patients and normal controls, suggesting that the promoter of CIITA gene might be a conserved domain.