Late in July and early in August 1942 there appeared in the wards of the Station Hospital at Fort Bragg, North Carolina, a group of soldiers who exhibited an unusual febrile illness. It shortly became apparent not only that these men had identical symptoms but that they all came from a few military organizations quartered near one another in a limited area of the reservation. Between July 29 and September 11, 40 such patients with this illness were admitted to the wards. The usual history was one of relatively sudden onset characterized by malaise, mild general aching, lumbar pain, severe frontal headache and postorbital pain. On the first or second day of symptoms mild respiratory manifestations consisting of coryza, sore throat, chest pain and soreness, and cough were complained of by 30 per cent of the patients. The respiratory symptoms were not persistent and were never suggestive of primary respiratory