We compared plasma content of soluble Fas antigen (sFas) in 59 patients with tumors and tumor-like pathologies of the adrenal cortex and medulla and 60 healthy donors (control). The incidence and content of sFas in the plasma from patients with adrenal tumors was significantly higher than in healthy donors. A direct correlation was found between sFas content and patient's age. The maximum sFas concentrations were found in patients with pheochromocytoma and aldosterone-producing adenoma. In patients with adrenocortical cancer plasma content of sFas was lower than in patients with tumors of other morphological types. Plasma sFas content in patients with adrenocortical cancer directly correlated with the size of tumors. Our results suggest that sFas plays a role in the pathogenesis of primary adrenal tumors.