BACKGROUND: Cigarettes kill an estimated 5 million people annually world–wide. By the early 2030, tobacco related death would increase to about 10 million a year. Tobacco smoking rates have decreased in industrialized countries since 1975, but there has been a corresponding 50% increase in smoking rates in low– income countries. The UN health agency reports that about 4.9 million people die each year across the globe due to cigarette smoking. AIMS AND OBJECTIVE : To study the differences in pulmonary function test values in smokers and non –smokers and their variation from other reported values for smokers by other studies. METHODS AND MATERIAL:–The study population comprised smoker group and non–smoker group and was carried out in the department of General Medicine at Madhubani Medical College, Madhubani, Bihar from September 2018 to August 2019 by using computerized spirometer in 100 male subjects comprising of 50 smokers and 50 non–smokers. RESULT: Almost all the pulmonary function parameters were significantly reduced in smokers and obstructive pulmonary impairment was commonest. The observed value of pulmonary functions in mean± standard deviation, FVC was 2.98 ± 1.06 litres, FEV1 was 2.48 ± 1.02 litres, FEV1 % was 83.93±23.98, PEFR was 5.30±3.46 litres/minute and FEF25–75% was 2.99±2.02 litres. The observed value of pulmonary functions in rural non–smoker population in mean± standard deviation, FVC was 3.13±0.98 litres, FEV1 was 2.81±0.86 litres, FEV1% was 89.49±10.54, PEFR was 6.80±3.44 litres/minute, and FEF2575% was 3.59±1.74 litres. CONCLUSION: There was significant decrease in pulmonary function in the rural smoker population in comparison to the non–smoker population