Serum levels of type IV collagen and hepatic type IV collagenase activity, as markers for formation and degradation respectively of basement membrane collagen (type IV collagen) in liver, were measured in patients with various alcoholic liver diseases. Development of alcoholic liver fibrosis seems to be due to both increased formation and decreased degradation of basement membrane collagen. Both measurements of type IV collagenase activity and serum level of type IV collagen were assumed to be useful to predict irreversible state of hepatic fibrosis.