<p>Pulmonary arterial hypertension (PAH) is a devastating disease complicated by pathological features such as proliferation of pulmonary artery smooth muscle cells (PASMCs), vasoconstriction, increased pulmonary artery pressure, and hypertrophic right heart failure. Among these features, excessive proliferation of PASMCs is the most significant pathological change in this disease. Lipid droplets (LDs) are ubiquitous cellular organelles that serve as energy storage sites. Previous studies have shown that large accumulations of intracellular LDs are observed in proliferating cells (such as stem cells and cancer cells) and that the modulation of LD accumulation can affect cell proliferation. These findings suggest that LDs play important roles in cell proliferation. This review aimed to investigate the role of LDs in PAH by focusing on the proliferation of PASMCs.</p>