Asymptomatic pulmonary infiltrates and eosinophilia developed in a patient with chronic ulcerative colitis 1 month after therapy with sulfasalazine had been instituted. The abnormalities resolved completely after use of the drug was discontinued. The sulfapyridine component of the sulfasalazine was the likely causative agent because 41 years earlier, the patient had experienced fever, myalgias, and eosinophilia after taking a sulfonamide. Ten previous cases of sulfasalazine pulmonary toxicity, including one fatality, have been reported.