All patients greater than 50 years of age (N = 96) admitted with a pre- or postoperative diagnosis of acute appendicitis from 1971 to 1980 were reviewed. A comparative series of 91 patients aged 25 to 50 years was similarly reviewed. Noninflammatory diseases of the appendix and incidental appendectomies were excluded. Detailed study of symptoms, clinical presentation, laboratory evaluation, radiographic evaluation, concomitant diseases, hospital course, surgical findings, complications, and mortality were completed. Comparison of patients aged 25 to 50 to patients older than 50 years revealed a statistically significant increased incidence of perforation in the older group (p less than 0.0001). Sixty-five per cent of the older group showed greater incidence of perforation. Further analysis of this series yields the hypothesis that the increased incidence of perforation is related to a significant decrease in the frequency of classic presentation in the greater-than-50 age group, a significant decrease in frequency of correct admission diagnosis and a significant delay between admission and surgical procedure in the older group. A more rapid pathophysiologic progression of appendicitis with increasing age was noted. A much higher percentage of older patients was undiagnosed until the surgical procedure. In this group, there was a longer duration of symptoms, less frequent classic presentation, and decreased frequency of right lower quadrant guarding and tenderness as compared to patients with correct diagnosis prior to surgery. Complications were much more frequent in older patients and higher still in those with perforation. Analysis of findings by decade of life revealed an anticipated high incidence of perforated appendicitis in patients greater than 50, but also showed a continuation of the high incidence of perforation into the decade 40 to 50. There were three deaths in the entire study group (1.6%) all occurring in the older age group with postoperative sepsis.