The relative merits of the anterior and posterior approaches to the adrenal gland were assessed in a series of 103 patients with bilateral cortical hyperplasia or unilateral cortical adenoma (less than 25 g). In none of the patients was additional concomitant surgery planned. Sixty-four patients were operated on through the anterior and 39 through the posterior approach. Iatrogenic injury of the spleen necessitated splenectomy in 9 (18 percent) of 49 patients undergoing left adrenalectomy anteriorly. In 10 (26 percent) of 39 patients operated on posteriorly, the pleural cavity was entered. Perioperative blood requirement and postoperative morbidity were lower when the posterior approach was used. The hospital stay was significantly shorter after both unilateral and bilateral adrenalectomy when operation was done through the posterior approach. The results of this study lend strong support to a posterior lumbar approach for adrenalectomy for small benign adrenal cortical lesions.