Background: The purpose of this study was to investigate if there was an association between ABO blood group and Rhesus factor (Rh) with dental malocclusion. Patients and methods: The sample of the current study consisted from 200 subjects (100 males and 100 females) collected at the College of Dentistry, University of Baghdad, Iraq. The antero-posterior relationships of the maxillary and mandibular first molars in maximum intercuspation by Angle’s classification were evaluated, the blood samples were collected. The examinations of blood grouping and Rh factor were done using slide agglutination method. Results: In Class I, the blood group O Rh+ve (55%), had a greater propensity for dental malocclusion. In Class II Division 1, also the blood group O Rh+ve (33%), had a greater susceptibility for dental malocclusion. While in Class II Division 2, the blood group O Rh+ve showed the predominant percentage of occurrence (41%). The Class III showed that the blood group O Rh+ve was the highest percentage (38%). There was no significant correlation (P>0.05) found between males and females in all malocclusions types. Also, there was no significant correlation (P>0.05) between all malocclusions types, blood grouping system, and Rhesus factor. Conclusion: The percentage of occurrence of total malocclusion was highest in blood group O Rh+ve, followed by A Rh+ve, B Rh+ve, B Rh−ve, AB Rh+ve, A Rh−ve, O Rh−ve respectively, and the AB Rh−ve was the least percentage (O Rh+ve>A Rh+ve > B Rh+veB Rh−ve > AB Rh+ve >A Rh−ve>O Rh−ve >AB Rh−ve). There was no significant association (P>0.05) between all malocclusion types, blood grouping system, and Rh factor.