A reduction in the number of postoperative bed days for patients who underwent appendectomy led to a study of changes in hospital costs of appendectomies for the years 1955, and 1965, and 1975. No significant changes were found in the total hospital costs. However, the postoperative costs decreased by 36 percent from 1955 to 1975 due to a decrease in the mean duration of hospital stay. During the same period of time, the perioperative costs increased by (table; see text) 90 percent due to increased length of operation time correlated with an increasing proportion of inexperienced operating surgeons. At present, there seem to be few possible ways to increase the cost efficiency of treating appendicitis.