Pulmonary arterial hypertension (PAH) is uncommon, yet life-threatening disorder characterized by increased pressure in the pulmonary arteries and progressive dysfunction of the right ventricle. It is designated as Group 1 within the World Symposium on Pulmonary Hypertension (WSPH) classification, reflecting its distinct clinical presentation and underlying pathological mechanisms compared to other PH subtypes. The primary cause of PAH is the narrowing and stiffening of the small pulmonary arteries, resulting from endothelial cell dysfunction, smooth muscle cells (SMCs) proliferation, and fibrosis. These alterations result in a rise in pulmonary vascular resistance (PVR), placing greater strain on the right heart as it attempts to propel blood through the pulmonary circulation, and eventually contributing to the elevation of pulmonary arterial pressure. Inflammation plays a critical role in the development and progression of PAH. It contributes to various pathological processes, including increased PVR and vascular remodeling, which further elevate pulmonary arterial pressure. Given its central role in PAH, inflammation has become a focus of therapeutic research. Anti-inflammatory treatments, such as cytokine inhibitors and immune modulators, have shown promise in preclinical studies and are currently being explored in clinical trials. This chapter summarizes current evidence implicating inflammation as a central contributor to the pathogenesis of PAH and explores its viability as a therapeutic target. Emphasis is placed on the necessity for continued investigation aimed at advancing anti-inflammatory interventions, with the goal of enhancing clinical outcomes for individuals affected by PAH.