All 527 postoperative haemorrhagic complications requiring reoperation from 1971 through 1980 were retrospectively analyzed. These operations constituted 1.2% of the total performed. Gastric resection, mastectomy and thyroid/parathyroid surgery showed significantly higher than average incidence of bleeding complications. No previously unknown cases of bleeding diathesis were detected. Drain was used in 34.5% of the primary operations, but rarely contributed to diagnosis of bleeding and did not reduce delay before reoperation. Shock or preshock was present in 15% of the patients. No source of haemorrhage was detected at 14% of the reoperations. Complications of various types were associated with 13% of the reoperations, with rebleeding and infectious conditions predominant. Complications of reoperation significantly prolonged the hospital stay, but did not raise the mortality rate. Mortality, however, was significantly higher after the reoperations than after the total primary operations during the study period (5.3 vs. 2.7%). Patients who had undergone arterial surgery were analyzed in more detail. There were 1.6% reoperations in this group. The bleeding emanated from anastomosis or arterial suture in only half of these cases and was then of two types--early, from technical causes or delayed, caused by infection.