The problem of diagnosis of peptic ulcer in children was analysed in a series of 50 consecutive cases. Atypical symptomatology occurred frequently and resulted in errors in diagnosis in six instances: perforated ulcer was misdiagnosed as appendicitis in five and bleeding ulcer was misdiagnosed as Meckel's diverticulitis in one. Barium meal was the investigation employed in earlier years but had proven unsatisfactory, being incorrect in four out of 22 examinations. Fiberoptic endoscopy was introduced in recent years and having achieved correct diagnosis in 20 patients with no errors, has established itself as the choice of investigation.