PURPOSE: Laparoscopic adrenalectomy has become the procedure of choice to remove a wide variety of adrenal tumors. The laparoscopic approaches to the adrenal gland include a lateral (transperitoneal) approach and the posterior (retroperitoneal) approach. The aim of the present study is to compare the clinical outcomes from both methods. METHODS: Between January 2000 and October 2008, we performed 60 laparoscopic adrenalectomies, including 29 posterior retroperitoneal approaches (RLA) and 31 lateral transperitoneal approaches (TLA). RESULTS: Sixty patients were treated for the following conditions: adrenocortical adenoma: 35 patients, pheochromocytoma: 19 patients, organizing hematoma: 2 patients, ganglioneuroma: 2 patients, myelolipoma: 1 patient and adrenal oncocytoma: 1 patient. The average tumor size was 3.2+/-1.4 cm in the TLA patient group and 2.9+/-1.4 cm in the RLA patient group. In the TLA group, the procedures were performed with the patients in the lateral position, and the patients were in the prone position in the RLA group. The average operation time of the RLA group was significantly shorter than that of the TLA group. The RLA group had a shorter postoperative hospital stay, they required less postoperative pain control and they resumed a full diet earlier. Conversion to open surgery was required in five patients (16%) in the TLA group. Complications occurred in five patients of the TLA group and in five patients of the RLA group. No mortality was observed in both groups. CONCLUSION: For experienced surgeons, if the adrenal tumor is less than 6 cm in size, posterior retroperitoneal adrenalectomy may be a safer and faster procedure, so it should be considered as the first choice of operation of benign adrenal tumors.