Exposure to the multiple toxins in tobacco smoke causes disease. Nicotine in tobacco plays a minor role, however addiction is the proximate cause for these smoke related diseases. Nicotine dependency leads to addiction that sustains the habit of tobacco smoking. To estimate the effect of nicotine dependency on the lung function of three different groups of asymptomatic tobacco smokers using spirometry. Institutional Ethics Committee approval was obtained. Adult male cigarette smokers (n=195) were recruited for this study based on their Fagerstrom’s nicotine dependence test score and were divided into four groups of 65 in each: Group I-less dependent, Group IImoderately dependent and Group III-highly dependent. Non-smokers(n=70) were selected as control group. After an overnight abstinence from tobacco use, the subjects were examined for their anthropometric parameters. Spirometry was done using RMS Helios 401,a PC based spirometer and the data were saved for later analysis. One way ANOVA with post hoc Tukey test was done using SPSS v17.0 with statistical significance set at p<0.05. Gradual and statistically significant decline in the spirometry was noticed. FEV1 values declined from control to group III(p<0.001). FVC values showed a negative correlation against increasing nicotine dependency. FEV1/FVC ratio, though showed a significant decrease(p<0.001) across the groups, it failed to categorize them with any COPD as the ratio was not <70% as per the new guidelines. Nicotine dependency worsens the respiratory functional status of the smoker. Increased nicotine addiction indirectly damages the lung function which can be brought down only by ceasing the tobacco use.