Periodontal disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. Several studies have focused on the relationship between ABO blood and RH factor groups and periodontal diseases. However, the results showed a lot of discrepancies Aim of the study: to evaluate the relationship between ABO, Rh blood groups and distribution of periodontal diseases. Material And Method: This study involved 560 subjects aged between 20 to 55 years; selected on random basis from the outpatient department of Periodontology at AL -mammon specialized dental center in Baghdad. The patients sample have been classified in a 3 groups in relation to their clinical presentation and the periodontal scores on a basis of Ramfjord’s Periodontal index. Result: out of 560 patients there were 312 male, 248 female patients. According to sample classification in relation to clinical condition and periodontal score, Group I 115 patients with healthy gingiva; group II 225 patients with gingivitis; and group III 220 patients with periodontitis ,the highest prevalence of periodontitis are among blood group O(34.1%), while higher gingivitis percentage are associated with blood group A (34.2%). The prevalence of gingivitis was higher in Rh positive group 43.1%, while periodontitis show higher prevalence in Rh negative group 40%. Discussion and conclusion: We concluded that there was significant relationship between ABO, Rh blood group system and periodontal disease. Blood group ‘A’ could be a factor of risk for gingivitis and blood group ‘O’ could be a factor of risk for the developing of periodontitis. Similarly Rh positive group considered a risk factor for gingivitis, while Rh negative group is a risk factor for periodontitis.