Background: Tobacco smoking is widely prevalent in developing countries and it has extensive effects on respiratory function and is a risk factor for a number of respiratory diseases. Early detection of lung function decline in smokers will be beneficial for promoting smoking cessation and reducing lung tissue damage. Method: This cross-sectional study was conducted in the rural and urban areas of Ghaziabad. We assessed the lung function in 150 healthy male smokers and 150 healthy non-smokers through spirometry. Results: The prevalence of smoking was higher in middle age group (38-49 years age group) as compared to older and younger ones. The spirometry parameters were significantly greater in non-smokers than smokers (p<0.001). Both smokers and non-smokers showed negative correlation between spirometry parameters and age (p<0.001). It was also observed that all spirometry parameters increased with increase in height in both the groups. Conclusion: Smoking leads to accelerated decline in lung function.