This study was conducted to investigate the association between genetic phenotypes of HLA-DQB1 with Grade B periodontitis and correlate the prevalence of HLA-DQB1 alleles and the clinical parameters of Grade B periodontitis in the Yemeni and Egyptian populations. 80 Yemeni and Egyptian Patients were selected to participate in the study. These patients were grouped into four groups, Egyptian patients with periodontitis (20 patients), Egyptian healthy controls (20 participants), Yemeni patients with periodontitis (20 patients), and Yemeni healthy controls (20 participants).