Numerous pharmacologic agents used in the treatment of cancer have been linked to pulmonary toxic side effects. Mechanisms of damage by these drugs include direct pulmonary toxicity and indirect effects through enhancement of inflammatory reactions. Risk factors for development of pulmonary damage have been elucidated for some agents but they remain unclear for others. Clinical features are similar for most categories of cytotoxic agents, and the most common associated clinical syndrome is chronic pneumonitis/fibrosis. Treatment and outcome vary with each particular agent. In Part 1 of this review, clinical aspects and pathogenic mechanisms of cytotoxic drug-induced pulmonary disease are discussed.