108 adult patients and 34 children with chronic active hepatitis (CAH) are divided in four groups on the basis of presence and absence of hepatitis B surface antigen (HBsAg) and autoantibodies (AutoAb). There are significant differences in the numeric distribution among the four groups and the sex distribution between adult patients and children, but no differences in the frequencies of the HLA antigens tested. An increased frequency of HLA-B8 (and HLA-Al) compared with normal controls and the other groups is only found in autoimmune types of CAH, characterized as HBsAg-negative, AutoAb-positive CAH. HBsAg-negative, AutoAb-negative forms of CAH are called cryptogenic CAH and these are most likely non-hepatitis B virus induced types of CAH. In these and hepatitis B virus induced forms of CAH no significant deviation of any HLA antigen tested could be found.