The authors report their experience with one-trocar transumbilical laparoscopic assisted appendectomy (TULAA). From January 1998 to June 2000,150 patients underwent appendectomy using this technique. Ages ranged from 2.5 to 17.4 years. The procedure was completed using only one trocar in 116 cases (77.3%); in 28 patients (18.7%) one or two additional cannulas were needed. Conversion to open surgery became necessary in 6 cases (4%). Mean operative time was 35 minutes, mean hospital stay 3.5 days. There were no major complications and no mortality in this series. The advantages of a one-trocar appendectomy compared with open surgery are the same as those reported for conventional laparoscopic appendectomy: i.e., excellent exploration of the abdominal cavity, the possibility of discovering extra-appendiceal lesions, easy and rapid localization of the appendix and a shorter hospital stay. The additional advantages of TULAA compared with conventional laparoscopic appendectomy are a low rate of intraoperative incidents, minimal scarring, less postoperative pain and a more rapid return to unrestricted activities.