Bleomycin is recognized to cause an interstitial pneumonitis that can lead to fibrosis. Although its occurrence may be sporadic, some factors may increase the risk of such a pulmonary reaction. In this article the clinical setting and presentation, radiographic manifestations, pathologic findings, and the prognosis of bleomycin-induced interstitial fibrosis are described. Additionally, the role of pulmonary function tests in monitoring patients for toxicity is discussed.