An original typed document signed giving the great violinist's blood type. June 2, 1944. On letterhead of the laboratories of Dr. M. J. Fein, New York, the document states that Heifetz has type B blood. Signed at the foot, with a further annotation in pencil at the head. Toning and folding creases with one slight split; overall very good. 6 x 9 inches (15.2 x 22.8 cm).