Background: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by vascular remodeling andsustained inflammation.KeyinflammatorymediatorslikeC-reactiveprotein(CRP),interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) are implicated in its pathogenesis and prognosis. Periodontal disease (PD), a chronic inflammatory condition of the oral cavity, is a known contributor to systemic inflammatory burden. While the link between PDandsystemic cardiovascular diseases is well-established, its specific relationship with the inflammatory milieu of PAH is poorly understood. Aim: This study aimed to investigate the correlation between periodontal disease activity and the levels of keyseruminflammatorymarkersinacohortofpatientswithstablePAH.Methodology:Weconductedacross-sectionalstudy involving 68 adult patients with a confirmed diagnosis of PAH (WHO Group 1). Participants underwent a comprehensive periodontal examination to assess Probing Depth (PD), Clinical Attachment Loss (CAL), and Bleeding on Probing (BOP). Based on the 2017 World Workshop classification criteria, they were categorized into two groups: Active PD (n=32) and No/Stable PD (n=36). Venous blood samples were collected to measure serum concentrations of high-sensitivity C-reactive protein (hs-CRP), IL-6, and TNF-α using enzyme-linked immunosorbent assays (ELISA). PAH severity was assessed using WHOFunctionalClassand6-minutewalkdistance(6MWD).KeyResults:PatientsintheActivePDgrouphadsignificantly higher median serum concentrations of hs-CRP (4.1 mg/L vs. 1.8 mg/L; p<0.001), IL-6 (5.2 pg/mL vs. 2.5 pg/mL; p=0.002), and TNF-α (3.9 pg/mL vs. 2.1 pg/mL; p<0.001) compared to the No/Stable PD group. The percentage of sites with BOP, an indicator of active periodontal inflammation, showed a significant positive correlation with hs-CRP (r=0.58, p<0.001), IL-6 (r=0.45, p=0.002), and TNF-α (r=0.51, p<0.001). These associations remained significant after adjusting for age, sex, and PAH severity. Conclusions: In patients with PAH, active periodontal disease is strongly associated with elevated levels of systemic inflammatory markers. These findings suggest that periodontal inflammation may contribute to the systemic inflammatory milieu in PAH. Further longitudinal research is warranted to determine if periodontal therapy can mitigate systemic inflammation and impact clinical outcomes in this vulnerable population.