A 35 year old primigravida with a triplet pregnancy developed polyuria and epigastric pain in the 31st week of pregnancy. During that week, emergency cesarean section was performed due to evidence of liver disease and imminent fetal hypoxia. Three girls were delivered who were healthy apart from transient neonatal respiration distress syndrome. Following surgery, the mother developed HELLP syndrome with hemolysis, increased transaminases and thrombocytopenia. She also developed diabetes insipidus with daily urine outputs of up to 7000 ml and poor response to desmopressin. Both the HELLP syndrome and the diabetes insipidus resolved spontaneously within ten days. In pregnant patients with right upper quadrant pain, HELLP syndrome or acute fatty liver of pregnancy should be considered. The association of diabetes insipidus with acute fatty liver of pregnancy is an established, but rare phenomenon. As far as is known, this is the first report of a patient presenting with a combination of HELLP syndrome and diabetes insipidus. Patients with HELLP syndrome have a good prognosis, if the diagnosis is early and the pregnancy terminated at the right time. With close supervision further pregnancies are possible.