OBJECTIVE To introduce our experience in using anatomic retroperitoneoscopic adrenalectomy (ARA) for adrenal tumors >5 cm and evaluate this procedure's safety and efficiency. METHODS Of the 1400 ARAs performed in the past 8 years, 110 were performed on patients who had adrenal tumors with a diameter >5 cm. The perioperative indexes of these patients were retrospectively collected and analyzed. RESULTS The mean tumor size on postoperative pathologic examination was 7.2 ± 2.1 cm (range 5-14). Only 1 patient with right-sided adrenal pheochromocytoma (7.8 cm diameter) required conversion to open surgery owing to the tumor's severe adhesions to the liver and inferior vena cava. The mean operative time and evaluated blood loss was 70.8 ± 18.6 minutes and 81.3 ± 46.1 mL, respectively. The average postoperative interval to oral intake and drainage withdrawal was 2.1 and 2.2 days, respectively. No patient died during the operation. Major intraoperative complication (ie, injury to the vena cava) occurred in 1 patient, necessitating open surgery. Minor complications during the perioperative period occurred in 10 patients (9.1%). CONCLUSIONS When performed by experienced surgeons, ARA is a safe and feasible procedure for large adrenal masses with a diameter >7 cm; however, this procedure results in a longer operation time and greater blood loss compared with ARA performed on smaller masses. Open surgery is indicated when the tumor adheres to, or has infiltrated, the surrounding tissues.