A total of 18 cases of Amanita phalloides poisoning was treated by combined chemotherapy during 1980 and 1981. After attempted primary elimination of the toxin all patients received silybin as basic therapy mainly by infusion and, in two instances, silymarin orally. In order to investigate the effect of silybin therapy a retrospective study of the followed-up case records was made. The cases were arbitrarily classified into three groups of severity (light, medium and severe) according to clinical and laboratory findings. A close relationship was found between the severity of the intoxication and the time elapsed before commencement of silybin therapy. The time interval between mushroom intake and the commencement of the silybin administration averaged 71.5 hours in the "severe" group compared with 46 and 33.8 hours, respectively, in the "medium" and "light" groups. The mean silybin dosage was 33 mg/kg body weight/day; the mean duration of silybin therapy was 81.6 hours. With the exception of one fatality in a particularly high dosage suicidal intoxication, all patients survived. Administration of silybin within about 48 hours after mushroom intake seems to be an effective measure to prevent severe liver damage in Amanita phalloides poisoning.