Conventional adrenalectomy requires relatively large incisions. To assess the value of retroperitoneal endoscopic adrenalectomy, a case-control study was performed comparing the endoscopic technique to conventional posterior adrenalectomy. All patients had adrenal tumors less than 7 cm in diameter. Endoscopic retroperitoneal adrenalectomy required more operative time (90 vs. 60 minutes, p < 0.0001) than the open approach but was associated with less blood loss (20 vs. 125 ml, p < 0.0001). Endoscopic adrenalectomy caused less pain postoperatively (p = 0.0005) and was associated with fewer complications (p = 0.035). The hospital stay was shorter after endoscopic adrenalectomy than after open adrenalectomy (p < 0.0001). In conclusion, we advocate endoscopic retroperitoneal adrenalectomy in patients with small adrenal tumors.