A 45-year-old female with a 4-week history of psoriatic arthritis developed cough, fever, and progressive shortness of breath 2 weeks following initiation of methotrexate therapy. High resolution CT of chest revealed bilateral basal interstitial involvement and diffuse ground glass opacities. Patient, though, died despite immediate discontinuation of methotrexate and initiation of treatment with IV methylprednisolone and cyclophosphamide. Post-mortem examination showed diffuse interstitial pulmonary fibrosis. Methotrexate-induced pulmonary toxicity is a serious event, unpredictable, and unusual, especially in patients with psoriatic arthritis, and although reversible, it may be fatal.