OBJECTIVE To analyze the lung damage caused by anticancer drug toxicity comparing the pathologic mechanisms, histopathologic response and CT features. METHODS Twenty-one patients (15 men and 6 women aged 21-75 years, mean: 41) were selected from the cancer patients treated with chemotherapy 1990 to 1997 (1400 lung examinations in all). The primary tumors consisted of: 6 testicular, 2 ovarian, 2 breast and 1 renal cancers; 3 non-Hodgkin lymphomas; 1 acute myeloid and 1 chronic lymphatic leukemia; 1 melanoma, 1 uterine leiomyosarcoma, 1 liposarcoma, 1 osteosarcoma and 1 head and neck carcinoma. All the patients underwent a CT examination with contiguous 8-10 mm slices and thin (4-5 mm) detail slices or with the high resolution technique. All the cases had clinical, laboratory and pathologic confirmation of the drug-related lung damage. RESULTS Four alveolar opacities, 11 interstitial opacities, 2 solitary and 4 multiple nodular lesions were demonstrated. Bleomycin was the most toxic drug in 14/21 cases, the total dose always exceeding 450 mg. Methotrexate followed and then cytosine-arabinoside (both 2/21). Bleomycin was responsible for all nodular lesions, cytosine-arabinoside and interleukin-2 for pulmonary edema. After drug discontinuation and appropriate treatment in 14 cases, we found favourable evolution with restitutio ad integrum (9 cases) or CT findings of clear improvement (5 cases); fibrosis progressed in 6 cases and one patient died. CONCLUSIONS CT provides important information for the diagnosis of drug-induced lung damage. Despite the nonspecific patterns of the lesions, CT can demonstrate the early, and thus potentially reversible, stages of lung damage. CT is also very helpful in monitoring the onset, resolution, or progression of fibrosis.