Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized primarily by increased proliferation and resistance to apoptosis in distal pulmonary arteries. Previous literature has demonstrated that the transcription factors NFAT (nuclear factor of activated T cells) and HIF-1α (hypoxia inducible factor 1α) are extensively involved in the pathogenesis of this disease and, more recently, has implicated STAT3 (signal transducer and activator of transcription 3) in their activation. Novel research shows that miR-204, a microRNA recently found to be notably downregulated through induction of PARP-1 (poly [ADP-ribose] polymerase 1) by excessive DNA damage in PAH, inhibits activation of STAT3. Contemporary research also indicates systemic impairment of skeletal muscle microcirculation in PAH and attributes this to a debilitated vascular endothelial growth factor pathway resulting from reduced miR-126 expression in endothelial cells. In this review, we focus on recent research implicating miR-204 and miR-126 in vascular remodeling processes, data that allow a better understanding of PAH molecular pathways and constitute a new hope for future therapy.Keywords: pulmonary arterial hypertension, microRNA, vascular remodeling, angiogenesis, skeletal muscle. Pulmonary arterial hypertension (PAH) is a severe disorder clinically defined by mean pulmonary arterial pressure of at least 25 mmHg at rest. 1 PAH patients display multiple symptoms that are not specific to PAH, including dyspnea, dizziness, and exercise intolerance. Mean age at diagnosis is around 45 years, although onset of symptoms can occur at any age. 2 Epidemiologically, it is estimated that between 20 and 50 persons per million suffer from this disease. 3 Physiologically, PAH is a vascular remodeling disease of various degrees that affects the adventitia, media, and intima of distal pulmonary arteries, leading to decreased lung perfusion and sustained elevation of pulmonary vascular resistance. 4 In response to this resistance, patients develop progressive compensatory right ventricular hypertrophy, which rapidly becomes insufficient and leads to dilatation and failure. 5,6 Histologically, PAH is associated with enhanced inflammation, proliferation, and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs). 7 Despite progress in treatment, medication remains limited and noncurative, and therefore PAH patients typically have poor prognoses (mortality rate of more than 10% after the first year of therapy) 8 and quality of life remains severely affected. The pathological mechanisms of PAH establishment need to be better understood and further studied because of their complexities and therapeutic interest. Indeed, knowledge regarding the molecular actors implicated in these impairments increases with each publication, revealing a complex process that remains far from being completely understood.In the past few years, literature has consistently implicated the role of microRNAs (miRNAs) in PAH. Briefly, miRNAs are s...