In this study, all of the voluntary blood donor records-11455 cases-were studied in Hamadan province blood transfusion organization from Feb, 1995 to Jan. 1996. The cases were investigated carefully ad included, HBS.Ag, sex, age, residence and marital status. The total percentage of HBS.Ag positive was 1.99% among blood donors. These figures showed that percentage of HBS.Ag positive cases had decreased in comparison with previous studies (0.97%). Geographically, the highest percentage of infection was specifically found in Toyserkan town (8.69%). The lowest was found in Hamadan (1.36%) and Ghorveh (1.3%). The age group between 15-24 had the lowest rate of infection (0.96%). The age group affected by the infection was between 58-68 (3.18%). This findings showed that percentage of males with HBS.Ag positive cases was 1.99% and females was 2.03%. Meanwhile, HBS.Ag positive cases in the married donors were 2.15% and 1.29% in the unmarried cases.