Gemcitabine is a nucleoside analog that is active in the treatment of various solid tumors. In general it is well tolerated and has few side effects. Pulmonary toxicity reported with gemcitabine use is usually mild and self-limiting. We present a case of severe pulmonary dysfunction after intravenous administration of a single dose of gemcitabine in a 58-year-old female patient with metastatic carcinoma of the pancreas. She developed tachypnea, marked hypoxemia, and an interstitial infiltrate on chest radiograph consistent with pulmonary edema, 4 days after receiving this drug. Diuretics and corticosteroids were beneficial in treating the acute respiratory failure. Pulmonary damage was completely resolved by means of clinical and radiological assessment. Because of the severity of this side effect, no further treatment with gemcitabine was given. Eventually, the patient died because of obstruction of the bowel due to progression of tumor growth. Publications concerning severe pulmonary toxicity due to gemcitabine are sparse. Pathophysiology and treatment are considered and a review of the literature is presented.