Molecular alterations induced by tobacco usage are not well characterized in oral squamous cell carcinoma. Tobacco consumption in chewing or smoking forms is a known risk factor in oral cancer. To understand proteomic changes due to tobacco usage in oral cancer patients we carried out comparative proteomic analysis in oral cancer patients who had history of tobacco using habits (patients who chewed tobacco and patients who smoked tobacco) and those with no history of tobacco consumption. Proteomic analysis resulted in the quantification of 5,848 proteins in smoker cohort, 5,216 in chewer, and 5,320 in non-user cohort. Among these 443, 72 and 139 were significantly dysregulated proteins (p-value≤ 0.05 and 2-fold change) in smoker, chewer and non-user cohorts, respectively. Gene ontology and pathway analysis of significantly dysregulated proteins revealed enrichment of distinct biological processes and pathways in each patient cohort. Proteins associated with collagen formation and antigen processing/presentation pathway were dysregulated in oral cancer patients who smoked tobacco, while keratinization process was enriched in patients who chewed tobacco. We also observed dysregulated proteins in non-users to be involved in ECM proteoglycans, metabolism of carbohydrates and glycosaminoglycans. Immune signaling pathways and muscle contraction were identified as common events dysregulated in all three cohorts. This study helps us to decipher the proteomic alterations induced by tobacco usage in oral cancer patients and will assist in identification of early detection markers to identify high risk population