The results of the experience with all cases of acute appendicitis occurring on the Surgical Service at Boston Children's Hospital between July 1, 1944, and January 1, 1957, are presented. There were 1,358 cases. Early diagnosis is of the utmost importance, although in small children this may be very difficult. Prompt appendectomy is the treatment for all children with appendicitis. The importance of adequate preoperative preparation and postoperative care of the sicker children is stressed. If appendiceal rupture has occurred, the appendix is removed and the abdominal cavity is drained. Of 1,358 cases, 611 (45%) had ruptured appendicitis. There was one death, a mortality of 0.07%. There have been no deaths in the last 12 years, during which 1,309 patients have been treated. The most common complications were residual infections and obstruction of the small bowel. Most of the immediate postoperative obstructions could be managed with a long intestinal tube. The fact that nearly half of the patients had rupture of the appendix before the time of hospitalization is strong proof that much has yet to be accomplished in improving the early recognition of this disease, thus permitting surgery to be performed before rupture and peritoneal soiling has occurred. The most important effort that can be made in this direction is (when the local physician cannot make frequent house calls to a sick child) to recommend 24 or 48 hours of observation in a hospital for any child in whom appendicitis is suspected. At little expense, this allows frequent checking by appropriate members of the resident or visiting staff of the hospital. If findings suggestive of appendiceal inflammation disappear, the child generally can be sent home the following day. For those in whom the abdominal findings become more impressive under observation, operation can be undertaken while there is still an opportunity to do so before appendiceal rupture has taken place.