A new technique of endosurgical pelvic lymph node dissection was performed for the staging of 10 prostate and 8 bladder cancers. The technique, involving an exclusive extraperitoneal space development with CO2 insufflation, is described in detail. Using the standard endosurgical (laparoscopic) equipment, we performed a complete bilateral ilio-obturator lymph node dissection in 15 patients (83%). In the remaining three patients, because of technical difficulties, only unilateral dissection was performed. The average operating time was 84 minutes. Morbidity was low (one instance of sepsis). Prospective assessment of CO2 homeostasis showed that arterial CO2 pressure (PaCO2) increased significantly but could be controlled by increasing minute ventilation output. Our results show that perioperative assessment of end-tidal CO2 partial pressure is necessary and sufficient for the adaptation of minute ventilation output. Two patients with prostate cancer had positive nodes. No intraoperative or postoperative morbidity related to the procedure was observed in patients submitted to radical surgery. Extraperitoneal endosurgical pelvic lymphadenectomy with CO2 insufflation is a rapid, safe, and effective method in the staging of urologic pelvic malignancies and represents an alternative to traditional open surgery as well as to conventional transperitoneal laparoscopic lymphadenectomy.