APPENDICITIS sometimes may threaten the life of the gravid patient, The diagnosis of acute appendicitis may be difficult under ordinary circumstances, but, in the pregnant patient, it represents an even greater challenge. Appendicitis is the most common extrauterine surgical complication of pregnancy,1and it occurs about once in every 1,000 pregnancies, being seen more frequently during the first two trimesters than during the last.2For a clearer understanding of the features and consequencies of appendicitis under these conditions, we have reviewed the recent experience at the Mayo Clinic. Observations During the ten-year period, 1954 through 1963, 34 pregnant women sought medical attention because of acute abdominal pain that led to the clinical diagnosis of acute appendicitis in pregnancy. Of these 34 patients, 20 were proved, by microscopic examination, to have acute appendicitis (an accuracy rate of 59%). Since there were 16,100deliveries during the period of this study, in our series the incidence of acute