Docetaxel, a new chemotherapeutic agent, has demonstrated activity in non-small cell lung cancer and breast cancer. Toxicities associated with treatment using docetaxel include hypersensitivity reactions and fluid retention, which can be prevented by pretreatment with corticosteroids. We describe herein two cases of acute interstitial pneumonitis after administration of docetaxel to patients suffering from metastatic non-small cell lung cancer. A pulmonary toxicity of docetaxel from an hypersensitivity reaction is likely because of symptoms course, radiological demonstration of an interstitial pneumonitis, lack of an infectious etiology and of clinical response to antibiotic treatment, and rapid recovery with corticosteroids. This unusual pulmonary toxicity has been rarely described with docetaxel, as transient pulmonary infiltrates have been observed during treatment with paclitaxel. The possibility of an hypersensitivity pneumonitis must be taken into account when a patient with docetaxel treatment presents pulmonary infiltrates.