3385 consecutive records of deliveries at the Ist Department of Obstetrics and Gynecology of the University Hospital, Vienna, were reviewed. Particular attention was paid to increased weight gain during pregnancy--defined as a total weight gain of more than 13,4 kg--and EPH-gestosis. Patients were put into one of two groups: (1) no increased weight gain during pregnancy, and (2) increased weight gain of over 13,4 kg. Each group was further divided into women with no or only slight symptoms of gestosis (gestosisindex 0 to 3) and gravidae with moderate or severe EPH-gestosis (gestosis index 4 or greater than 4). The four groups of gravidae were compared with regard to perinatal complications and fetal outcome. While the average weight gain for all gravidae was 13,2 kg, patients with EPH-gestosis did not gain significantly more than non-gestotic women. However, body-weight before pregnancy was positively correlated with the symptoms and the severity of EPH-gestosis. It was concluded, that weight gain per se has very little, if any influence on the appearance of toxemia. Patients, who are overweight at the onset of pregnancy must be considered at risk for the development of moderate or severe EPH-gestosis.