Background: Human periodontal disease comprises a heterogenous group of infectious diseases that lead to pathologic destruction of the periodontium. Periodontal diseases have varied aetiology i.e. bacterial, host response and clinical disease progression. The most important blood-typing system, the ABO blood group, is the determinant for transfusion reactions and organ transplantation. Here in this study we will be investigating the prevalence of chronic periodontitis in patients with different blood groups. Material and Methods: A total of 875 subjects in the age group of 25 yrs and 45 yrs and of both sexes with equal percentage of males and females were selected at random, belonging to Rishikesh, Uttarakhand. The study subjects were grouped into healthy/mild gingivitis, moderate/severe gingivitis, and periodontitis group, based on Loe and Silness index and clinical attachment loss as criteria. The study group was further categorized and graded using Ramfjord’s periodontal disease index. Further blood investigations were made to detect the blood group. Results: It was concluded that the blood groups B and A were associated with diseased periodontium. Conclusion: The prevalence of blood group A is more in this geographic location, followed by blood groups B and O, and the least prevalent was blood group AB. There was an increased prevalence of subjects with blood groups A and O with healthy periodontium, while blood groups B and A showed inclination toward diseased periodontium. This association can be due to various blood group antigens acting as receptors for the infectious agents associated with periodontal disease.