The precipitation of acute disseminated lupus erythematosus in patients with the discoid or subacute type by ultraviolet radiation is well known. Overexposure to sunlight or to the mechanical ultraviolet radiation generator has often been found responsible. The subject has been well reviewed by Bechet.1The literature back to 1916, however, contains no case report of the syndrome following roentgen irradiation. Keil2stated in 1937 that it may occur but did not document his statement. The following report concerns a patient in whom acute disseminated lupus erythematosus was apparently precipitated by roentgen irradiation. REPORT OF A CASE M. v. T., an American housewife aged 70, was admitted to the Johns Hopkins Hospital on Feb. 3, 1940, complaining of a generalized eruption, weakness and fever. Her father, mother and 2 paternal aunts had had tuberculosis. Cardiovascular renal hypertensive disease had been common in the maternal forbears. Her mother's brother died