OBJECTIVE: To evaluate the feasibility of using low-dose computed tomography (LDCT) for the early diagnosis of lung cancer and malignant pleural mesothelioma in an asbestos-exposed population. METHODS: Between February 2002 and October 2003, 1,045 volunteers already enrolled in a surveillance program for asbestos-exposed workers and former workers were recruited. The main eligibility criteria were: written informed consent, definite exposure to asbestos, age 40-75, no prior cancer or severe concomitant conditions, no chest CT scan in the past 2 years. A smoking history was not required. After a structured interview, chest X-ray (CXR) and LDCT were performed. Participants with negative examinations were assigned to annual LDCT. Participants with positive findings received high-resolution CT and additional diagnostic workup as appropriate. RESULTS: Baseline characteristics of the screened population were: median asbestos exposure time, 30 years; median age, 58; median pack-years in smokers/former smokers, 18.5. Thirty-four percent had never smoked. On LDCT, 834 noncalcified nodules were identified in 44% of participants, versus 43 nodules in 4% on CXR. Pleural abnormalities were observed in 44% and 70% of participants by CXR and LDCT, respectively. Overall, LDCT identified nine cases of non-small cell lung cancer-eight stage I, one stage IIA-and one thymic carcinoid, corresponding to 1% of the enrolled population. All cases were radically treated. None had been detected by CXR. No pleural mesothelioma was diagnosed. There were 11 false-positive results. CONCLUSIONS: Our findings first suggest that LDCT may be at least as useful in asbestos workers as in heavy smokers for the early diagnosis of lung cancer; this benefit is evident even in a poor-risk population, with low rates of smoking prevalence and a previous history of radiological surveillance. The role of spiral tomography in screening for pleural mesothelioma remains uncertain.