Acute fatty liver of pregnancy (AFLP) and the syndrome of hemolysis, elevated liver enzyme levels, and low platelet count (HELLP) are rare but major disorders of the third trimester of pregnancy. Over a 10-year period, 46 women (median age, 30 years; range, 17-41 years) developed hepatic dysfunction severe enough to require transfer to our Liver Failure Unit. Three quarters of the women were nulliparous, and 5 had twin pregnancies; the median gestational age was 35 weeks (range, 24-40 weeks). At admission, 32 patients (70%) were preeclamptic and 21 (46%) were encephalopathic and/or ventilated. Thirty-two patients (70%) had clinical features and laboratory values consistent with AFLP, and 7 (15%) had HELLP syndrome. One patient had preeclamptic liver rupture requiring liver transplantation. In 6 other patients, causes of severe liver dysfunction unrelated to pregnancy were found. Infectious complications occurred in 17 of the patients with AFLP (53%) and in 2 of those with HELLP syndrome (29%). Major intra-abdominal bleeding occurred in 12 women (10 with AFLP), 9 of whom required laparotomies for clot evacuation. Four patients with AFLP (12.5%) had a fatal outcome, with a corresponding perinatal mortality rate of 9%. There were no maternal or perinatal deaths associated with HELLP syndrome. In contrast to results of many previous studies, the results of this large series suggest a relatively favorable maternal and perinatal outcome in severe AFLP and HELLP syndrome. Further improvements in outcome are likely to be achieved through the prevention of the bleeding and infectious complications associated with these disorders.