We observed a decrease in serum bilirubin, alkaline phosphatases (ALP) and IgM in five patients with primary biliary cirrhosis (PBC) treated with Prednimustin (Sterecyt) for 6 months. In contrast to pretreatment findings, C3 activation was undetectable during treatment in three patients where normalization of serum IgM was achieved. After discontinuation of Prednimustin, bilirubin and ALP levels rapidly returned to pretreatment values, although IgM remained normal for up to 6 months in some patients. We conclude that Prednimustin might be of value in patients with symptomatic PBC where liver transplantation is not an option, and that it should be evaluated in a controlled study. However, the rapid reactivation of the disease after conclusion of treatment must be considered.