Ligation of the inferior vena cava was performed on 38 patients with five postoperative deaths (13%). Recurrent pulmonary embolism occurred in three patients (8%) and on late follow-up, eight (24%) had minimal lower extremity stasis symptoms, 11 (33%) had moderate symptoms, and 14 (43%) had signs of the postphlebitic syndrome in one or both legs. Partial caval interruption was performed on 26 patients with two postoperative deaths (8%). Recurrent embolism occurred in two patients (8%) and on late follow-up, 13 (54%) had minimal lower extremity stasis symptoms, seven (30%) had moderate symptoms, and four (14%) had signs of the postphlebitic syndrome. The findings indicate that partial interruption is as effective as ligation in preventing pulmonary embolism, is associated with a lower operative mortality, and is followed by significantly less disabling stasis sequelae in the lower extremities.