The aim of the study was to present the authors' four-year experience in employing posterior retroperitoneoscopic adrenalectomy according to Walz (PRA) in surgical treatment of adrenal tumors up to 6 cm in size.Material and methods. A prospective analysis included 83 procedures of unilateral PRA (40 rightsided and 43 left-sided adrenalectomies) performed in patients (the M:F ratio = 22:61; mean age 58.1±10.3 years; mean tumor size 41±14 mm) operated on in the Department in the period from January 2004 to December 2007. Indications for surgery included: glucocorticoid adenomas (10), aldosteronomas (18), pheochromocytomas (16) and hormonally inactive adrenal cortex tumors (39). The operators used the PRA surgical technique according to Walz. The learning curve was evaluated taking into consideration the operative time, percentage of conversions and complications. The statistical analysis assessed the correlation between the operative time and body mass index (BMI), location and size of the tumor and its hormonal activity. The results of surgical treatment employed in patients with hormonally active tumors were evaluated in a 6-month follow-up.Results. The mean operative time was 73.7±22.3 min. A single conversion (1.2%) was required, as well as a single early reoperation (1.2%) due to bleeding. Following the initial 20 operations with the mean operative time of 86.5±34.6 min, the mean operative time of the remaining 63 procedures was 69.7±14.9 min (p=0.046) and did not exceed 90 min in any case. No correlation was noted between the operative time and BMI, tumor location and size. The procedures performed in patients with pheochromocytomas were not significantly longer in comparison to operations in hormonally inactive adrenocortical adenomas. Normalization of arterial blood pressure was achieved in all the patients with pheochromocytomas, aldosteronomas and subclinical glucocorticoidism aged below 50 years and with less than one-year history of secondary hypertension.Conclusions. Despite its seeming complexity resulting from operating in an "upside down" surgical field, the PRA surgical technique is easy to master and safe, also during the learning period. After the surgeon has performed approximately 20 operations, the operative time does not exceed 90 min. PRA is worthy of recommending in the case of adrenal tumors qualified for surgical treatment and not exceeding 6 cm in size.