The purpose of this study was to examine the effects of smoking habits on physical fitness and blood pressure of middle-aged male workers considering the effect of body mass index which would be decreased by habitual smoking. The subjects were 3376 middle-aged men who worked at two enterprises in Hiroshima prefecture. The effects of habitual smoking on physical fitness and blood pressure were evaluated by two models of analysis of covariance (PC-SAS: GLM procedure) involving several confounding factors. Model 1 involved such confounding factors as body mass index, age, drinking habits, physical activity, working system and type of job, and model 2 involved the confounding factors except body mass index in model 1. In model 1 the effect of body mass index was adjusted, and in model 2 the effect of body mass index was reflected in the results of analysis. The main results are summerized as follows: 1) Smokers indicated lower body mass index than non-smokers. 2) Smokers indicated higher vertical jump score than non-smokers. 3) Smokers indicated lower side step test and step test scores than non-smokers, suggesting that smoking habits could influence anaerobic exercise ability and cardiorespiratory functions. 4) Smokers indicated significantly lower systolic blood pressure level than non-smokers only in the result of model 2. So it was recognized that systolic blood pressure was decreased by both effects of habitual smoking and decreased body mass index as a result of habitual smoking. 5) Decreased body mass index in smokers had no benefical effects for side step test and step test scores.