Background: Obesity increases the risk of cardiovascular disease, hypertension, diabetes, and other disorders. Several studies have shown that excess weight or weight gain was related to the decline of pulmonary function. This study is to find out whether pilot,s age, height, body weight, body mass index(BMI) and smoking are related to the baseline measurement of pulmonary function in order to promote the healthy behavior of pilots. Method: The analysis was based on data from the annual physical examination of pilots which was conducted in one airlines company of Korea. This study compared the data obtained from 73 pilots in 1996 with the data in 2002. Pulmonary function(forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and maximal mid expiratory flow (MMEF), peak expiratory flow (PEF)), age, height, body weight and body mass index were measured in both surveys. Multivariate analysis of variance (MANOVA) was used to examine the relationship weight gain, smoking and pulmonary function. Results: According to the data from 2002, mean age, mean height, mean body weight and mean BMI of pilots were examined: 47.62 years, 171.60 cm, 70.6 Kg and 24.03 Kg/m2. Age was significantly related to FVC, FEV1 and MMEF. Height was significantly related to FVC and FEV1. However, body weight was significantly related to PEF and MMEF. The effect of smoking on pulmonary function was not significant. Pilots who gained body weight and BMI after 7 years were not related significantly to the pulmonary function. Conclusion: This study shows that age, height, weight are significantly related to pulmonary function. And other studies show that weight gain is significantly related to the decline of pulmonary function, but the relationship from this study is not significant because the number of sample is not enough and healthy behaviors of most pilots are relatively well.