May-Thurner syndrome, a pelvic vein congenital anomaly is the consequence of compression of the left common iliacal vein by the overlying right common iliacal artery that results in an increased risk for ileofemoral deep vein thrombosis. Authors present a case of a young female with aberration of the pelvic vein, who had also heterozygous Leiden mutation. After confirmation of the diagnosis of May-Thurner syndrome, plastic surgery of the common iliacal vein was performed and anticoagulant treatment was given. Orv. Hetil., 2011, 152, 139–141.