[Pulmonary disease induced by methotrexate].

A 68-year-old man with rheumatoid arthritis developed methotrexate-induced lung disease. He presented with fever, cough, respiratory distress and pulmonary infiltrates, which were initially mistaken for pneumonia. Alertness to this rare and dangerous complication of methotrexate treatment will reduce possible damage and help maintain its place as a leading medication for rheumatoid arthritis.