The link between cigarette smoking and lung cancer is well documented. The introduction of autofluorescence bronchoscopy (AFB) has allowed visualization of preinvasive neoplastic changes of bronchial mucosa. We evaluate the sensitivity of AFB to show epithelial changes compared with white light bronchoscopy (WLB) in a group of healthy, asymptomatic smokers. Inclusion criteria demanded heavy smokers (>20 pack-years) at least 40 years old, asymptomatic with no history of cancer and clear chest x-ray. Candidates completed a questionnaire and were interviewed to record medical history and smoking habit. Bronchoscopy was carried out under topical or general anesthesia with standard flexible fiberoptic bronchoscope for WLB and the Xillix LIFE Lung system for AFB. The study included 93 subjects (57 men, 36 women) aged 40 to 75 years. AFB indicated positive images in the bronchial tree of 51 subjects, biopsies showed epithelial abnormalities in 27 (15 metaplasia, 12 inflammatory changes). WLB showed abnormality in 1 subject but with no pathologic changes revealed by cytohistology. Therefore, the sensitivity of AFB to metaplasia was 75% compared with zero for WLB. AFB yields positive predictive values for metaplastic and overall mucosal changes of 29.4% and 52.9%, respectively. Over 16% of asymptomatic smokers had metaplastic changes in their bronchial mucosa. AFB proved more sensitive in revealing early preneoplastic changes than WLB. We suggest the follow-up of such individuals to evaluate progress particularly in those who continue to smoke.