Summary. In previous reports the results of appendectomies were commonly given as lethality observed in individual hospitals over fairly long periods of time. The lethality was similar in different countries and depended mainly on the inflammatory stage and patients' age. Recent studies, however, have pointed out remarkable differences in the mortality of appendicitis in several countries. The mortality figure like 3.3 deaths/100000/year in Germany is three to four times higher than in comparable countries as England, Sweden, and USA. The same difference is found in the figures of appendectomy frequency between these countries. This parallel does not represent, however, a causality between high mortality and high operative frequency in Germany as indicated by an analysis of 77 cases, the total of casualties over a 4-year period in Hannover metropolitan area. In 83°/0 of these cases an advanced inflammatory stage of appendicitis had prompted appendectomy. Thus, the high mortality can not be due to the high frequency of supposedly "unnecessary" appendectomies. On the other hand there were 10 deaths among the chronic appendicitis'. The exact indications for appendectomy therefore need further evaluation.