The effect of cigarette smoking in relation to bone mineral density (BMD) remains inconclusive, especially in middle-aged men. This cross-sectional study was conducted to examine the effect of smoking on BMD in 837 healthy Taiwanese males (532 never-smokers, 258 current smokers, 47 former smokers; aged 46-64 yr), recruited at their routine health examination. Subjects with suspected conditions affecting bone metabolism or receiving any medications affecting bone metabolism were excluded. BMD of the lumbar spine (LSBMD) and femoral neck (FNBMD) was measured with dual-energy X-ray absorptiometry. After adjustment for confounding variables (age, weight, physical activity, alcohol consumption, and caffeine intake), we found that the mean value of LSBMD was significantly (2.9%) lower in current smoker compared with never-smokers (p=0.024), but no significant difference was observed in FNBMD. No statistically significant association was observed between former smokers and never-smokers in any of the BMD sites, indicating that quitting smoking did have a positive effect on bone density. Compared with never-smokers, current heavy smokers who consumed at least 20 cigarettes/d (n=94) had 3.8% lower LSBMD (p=0.04), but no significant difference was observed in FNBMD. In the correlation analysis, the duration of smoking was negatively associated with LSBMD (r=-0.166, p=0.004), but no association was shown in FNBMD. Our results suggested that both smoking status and duration of smoking were deleterious factors on the bone density of the lumbar spine, and the effect was cumulative with duration and quantity.