Delay in appendectomy occurs from failure to contact a physician, or from a physician's failure to make a proper diagnosis. In our study delay was due to physician error in 32 of 422 children who had appendectomy. Symptoms consistent with appendicitis were documented on the initial visit in each case, but 22 patients had a history of previous similar pain or recent viral illness to confuse the diagnosis. Misdiagnosis was responsible for the delay in 14 cases (gastroenteritis in ten and urinary tract infection in four). Antibiotics given before proper diagnosis in 22 instances increased diagnostic difficulty in 20. Late referral is increasing, perhaps because of a perceived innocuous nature of appendicitis. Complicated appendicitis was found in 26 children (81%), compared with 38% of the total experience. Their hospital stay averaged nine days, as opposed to 6.6 days in the nondelayed group. Failure of resolution of symptoms after therapy begins mandates reassessment to avoid progression of this common surgical disease.