Objective: To assess our current concept and results of transperitoneal laparoscopic adrenalectomy (TPLA) and retroperitoneal endoscopic adrenalectomy (ERA) for a variety of benign disorders of the adrenal glands. Background Data:According to the literature, minimal invasive adrenalectomy has shown to be a safe and effective surgical alternative to open adrenalectomy. Both, transperitoneal and retroperitoneal endoscopic minimal invasive access are currently used for surgical removal of benign adrenal tumors. There is still some debate about the indications and the access used for a minimal invasive approach. Patients and Methods: Treatment and clinical outcome of all patients who underwent either transperitoneal laparoscopic or endoscopic retroperitoneal adrenalectomies for benign diseases from February 1997 to August 2002 were analyzed retrospectively. Results: Twenty-six minimal invasive adrenalectomies were performed in 23 patients with a mean age of 57 years. Whereas 11 patients underwent unilateral right- sided ERA, unilateral TPLA was performed in 9 patients on the left side. Three patients had bilateral TPLA. The mean operating time for unilateral ERA and TPLA was 114 and 79 min, respectively. Bilateral TPLA was prolonged to 223 min operating time. There were only two minor postoperative complications. The mean hospital stay for unilateral TPLA, ERA and bilateral TPLA was 4.7, 5 and 6 days, respectively. There was no mortality. Conclusion: Both, ERA and TPLA are safe and clinically effective treatment modalities for benign disorders of the adrenal glands. We currently favor a transperitoneal laparoscopic approach for bilateral and left-sided adrenal tumors, whereas right-sided tumors <8 cm are removed by a retroperitoneal approach. Large right-sided tumors >8 cm are better removed by transperitoneal access.