In order to document the incidence of perioperative complications in patients with infantile hypertrophic pyloric stenosis, a descriptive cohort study was performed in two teaching hospitals in the Netherlands. One hospital specialized in pediatric surgery and the other was a general surgery teaching hospital. All consecutive infants who underwent pyloromyotomy for the diagnosis hypertrophic pyloric stenosis in both hospitals between 1998 and 2002 were included. The children were diagnosed and treated according to a standard protocol. From all charts, complications durante- and post-operationem were recorded. A total of 256 pyloromyotomies were performed. Registered perioperative complications were duodenal mucosal perforation (n=6; 2%). Perioperatively unrecognized duodenal mucosal perforation occurred four times (1%). One re-operation was performed for an incomplete pyloromyotomy (0.3%). Persistent vomiting after the operation occurred in 18 children (7%). A large majority of postoperative complications were wound infections (n=16; 6%), 12 after right upper quadrant incision and 4 after umbilical incision; most of them were treated with antibiotics and/or incision for drainage of an abscess. An incisional hernia occurred four times. Prolonged vomiting was the only postoperative complication that differed significantly between the two teaching hospitals. The overall percentages of complications were equal to complication rates in literature, and since there were no extensive differences in major complications between the two teaching hospitals in this study, we can conclude that pyloromyotomy can be performed safely in specialized centers and in general centers provided with a multidisciplinary team.