OBJECTIVE Laparoscopic adrenalectomy has become an effective option for aldosteronoma. We evaluated the retroperitoneal approach with regard to safety, efficacy, invasiveness and cost-benefit ratio in patients with primary aldosteronism. METHODS Between July 1999 and June 2005, we carried out a total of 195 retroperitoneoscopic adrenalectomies (RA) in one hospital, including 108 on the left and 87 on the right, in 78 men and 113 women aged 20-78 years (mean age 48.2 years) with aldosteronoma. Average adrenal tumor size was 16 mm (range 10-32 mm). The 195 operations were divided into 10 groups of 20 operations each, and the mean duration and estimated blood loss for each group were compared. RESULTS The mean operating time and intraoperative blood loss in RA were 93.2 +/- 37.4 (45-210) min and 68.5 +/- 53.2 (5-210) mL, respectively. Compared to group 1 (cases 1-20), a statistically significant decrease in operative time and estimated blood loss were seen in and after group 4 (>or= case 61, 94.5 +/- 30.3 vs 139.2 +/- 44.7 min, P < 0.01), and in and after group 5 (>or= case 81, 67.5 +/- 50.5 vs 120.5 +/- 60.9 mL, P < 0.01), respectively. No differences were found in duration of surgery and estimated blood loss between left and right sided tumors (P > 0.05). The mean postoperative hospital stay was 4.5 +/- 1.2 days. Postoperative complications, including hematoma and wound infection, occurred in 4.1% of patients. CONCLUSIONS Retroperitoneoscopic adrenalectomy for aldosteronoma is a safe, effective, and minimally invasive approach with an advantageous cost-benefit ratio. With accumulated experience, it can expedite the learning curve for RA.