BARON Constantin von Economo was a man of varied background and interests.1,2 Of Greek descent, von Economo was born in Rumania in 1876, studied in Austria, France, and Germany, and worked in Vienna until his death in 1931. In addition to his medical accomplishments, von Economo was a pioneering balloon and airplane pilot and enthusiastically promoted international aviation meetings. His work in psychiatry and neurology was carried out in the clinic of Julius Wagner von Jauregg at the University of Vienna, and it was there that he detected encephalitis lethargica. As an outgrowth of his interest in encephalitis, von Economo also made important contributions to the study of the cerebral control of sleep. In all, 27 of his publications concerned encephalitis lethargica, including a book published in his last years.3 Von Economo's disease was the first epidemic of encephalitis to be clearly recognized and described. It raged