Context: Smoking continues to be the single most preventable source of health hazards. A detailed analysis of impact of duration of smoking, intensity of smoking on the hematological parameters in current smokers, ex-smokers and non smokers is lacking. Aims: The objectives were to study the effect of smoking and its intensity on hematological parameters in chronic smokers and to compare it with that of in ex-smokers and non smokers. Materials and Methods: Adult male chronic smokers and exsmokers were interviewed about their smoking pattern and the results of their hematological parameters were collected. The results of the same hematological parameters from non smokers were also collected for comparison. The collected data were entered in excel and analyzed by statistical tests. Results: Out of 133 participants, 47 were current smokers, 45 were ex-smokers, and 41 were non smokers. Majorities (59%) of the current smokers were from the age group 31-50 and ex-smokers (53%) were from the age group 51-70. Majority (81%) of the current smokers were smoking 1-10 cigarettes per day for duration of 16- 30 years (62% of the smokers). On comparing the hematological parameters among current smokers, ex-smokers and non smokers, it was found that chronic smokers had statistically significant (P value < 0.05) elevated levels of MCH, MCHC, Neutrophils and Lymphocytes compared to that of non smokers. Conclusion: Chronic smoking causes altered hematological parameters. Abnormal parameters in current smokers return to near normal after quitting smoking.

Keywords: Smoking, Hematological Parameters; Current Smokers; Ex-Smokers; Non Smokers.