Gemcitabine therapy has been associated with pulmonary toxicities but not specifically with bronchiolitis obliterans organizing pneumonia. Gemcitabine (2′2′-difluorodeoxycytidine) is a pyrimidine analog of deoxycytidine, similar to arabinoside, which intercalates into the DNA of actively dividing cells. It is used in the treatment of breast, pancreas, bladder, ovary, and non-small cell lung cancers. Mild toxicities include myelosuppression, fatigue, peripheral edema, and transient elevations in transaminase enzyme levels. Dyspnea has been reported in up to 23% of patients in clinical trials using gemcitabine. The incidence of dyspnea was highest in those patients who were treated for primary or metastatic lung cancer. Abrupt shortness of breath has been described as occurring within a few hours of the administration of the drug without associated radiographic changes or hypoxemia; symptoms abate with the discontinuation of treatment. It is thought that this acute dyspnea is from bronchospasm. Other reported pulmonary toxicities are rare, including fatal or life-threatening ARDS, pneumonitis, noncardiogenic pulmonary edema, pulmonary fibrosis, pulmonary hemorrhage, diffuse alveolar damage, and pulmonary venoocclusive disease. Pavlakis et al described three patients who had been treated with gemcitabine, two of whom died. The third patient with advanced ovarian carcinoma received nine cycles of gemcitabine, during which dyspnea and fevers developed. Transbronchial biopsy revealed nonspecific interstitial pneumonitis consistent with drug-induced lung toxicity. Corticosteroid treatment induced progressive improvement of the patient’s pulmonary symptoms.