ACUTE pulmonary response to short-term therapy with nitrofurantoin was described first in 1962 and was followed in 1966 by the description of a severe, debilitating, subacute pulmonary response. 1 Since that time, 40 subacute and chronic pulmonary responses to long-term nitrofurantoin therapy have been recorded in the English medical literature, and biopsy specimens in some have shown the process to resemble desquamative interstitial pneumonia. 1-15 It is generally considered that the correct treatment is to discontinue administration of the offending agent and substitute a course of oral corticosteroids. Report of a Case A 59-year-old man was seen in September 1978 with a history of productive cough and progressive dyspnea. In 1976, a right lower lobectomy following trauma had disclosed some interstitial pulmonary fibrosis. Chest x-ray films obtained on the current admission showed bilateral basilar interstitial fibrosis and pleural thickening. A previous roentgenogram in September 1977 had been normal. On this