Meckel's diverticulum occurs in 2% of the population and may present at any age. Its management, when found incidentally at laparotomy, remains controversial, particularly in the pediatric population. From 1970 to 1989, a Meckel's diverticulum was discovered in 164 children at laparotomy. There were 120 boys and 44 girls with a mean age of 5.2 years (range, 0 to 18 years). Forty-seven cases were asymptomatic, representing an incidental finding at laparotomy, 25 were resected, and ectopic gastric mucosa was present in 7 specimens (28%). Three postoperative deaths (6%) that were not related to the resection and 2 complications (4%) (postoperative leak and wound infection) occurred in this group. Of the 117 symptomatic patients, 49 (42%) presented with bowel obstruction, 45 (38%) had rectal bleeding, 16 (14%) had diverticulitis, and 7 (6%) had umbilical pathology. Volvulus (20) and intussusception (19) were the most common causes of obstruction. Predisposing factors for bowel obstruction were fibrous bands to umbilicus or mesentery (37%) and ectopic mucosa (35%). Severe painless rectal bleeding occurred in 45 patients, 30 of whom (67%) required blood transfusion. A nuclear medicine Meckel scan was positive in 32 of 37 patients (85%). Contrast studies were not diagnostic; colonoscopy and gastroscopy ruled out other causes of bleeding. Patients with diverticulitis (16) presented with acute abdominal pain compatible with appendicitis. In the symptomatic group, ectopic mucosa was present in 61% of the resected specimens. Gastric (88%), pancreatic (7%), and gastric with pancreatic (3%) were the most common ectopic tissue. Postoperative morbidity and mortality for symptomatic patients was 8.5% and 0%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)