A review of cases of primary adenocarcinoma of the appendix seen at the Hines VA Hospital (1950-1987) and Loyola University Medical Center (1977-1987) revealed a total of 14 cases. All patients presented with a clinical picture suggesting acute appendicitis or a right lower quadrant mass. Malignancy was not suspected in any of the patients prior to surgery. The age group ranged from 25 to 66 years (mean, 51.8 years) with 29% of the patients under 45 years old. The presence of carcinoma should be carefully looked for in middle-aged and elderly patients presenting with acute appendicitis.