The quadrilateral space syndrome is defined as tenderness over the quadrilateral space and shoulder pain radiating to the arm, secondary to compression of the axillary nerve and posterior circumflex humeral artery in the quadrilateral space. The symptoms are aggravated by forced abduction and extrenal rotation of the arm. The diagnosis is clinical and is documented by arteriography or angio-MR imaging with dynamic maneuvers. A 30-year-old woman presenting with this syndrome is described here, the differential diagnosis discussed, and the literature reviewed.