The reduction in mortality in acute appendicitis during the past 40 years constitutes a remarkable achievement. Unfortunately, there remains a comparatively high death rate in this disease in small infants. Evidence exists that this is due, in part, to a lack of progress in the early diagnosis of this disorder. It appears that the great advances in technical and therapeutic procedures have obscured the importance of early diagnosis. For this reason it seems worth while to review the factors responsible for delay in diagnosis and to discuss some of the associated problems. This study concerns itself with (a) a report of acute appendicitis with perforation in a 15-day-old infant with survival; (b) an analysis of acute appendicitis in infants 36 months of age or younger, from 1942 to 1952, at the Los Angeles County Hospital, and (c) a survey of the literature. Acute Appendicitis in a Fifteen-Day-Old Boy A full-term