Children and adults with pulmonary arterial hypertension (PAH) have similarities and differences in their background characteristics, hemodynamics, clinical manifestations, response to medical treatment and prognosis. In the majority of paediatric patients, PH is idiopathic or associated with congenital heart disease and rarely, is associated with other conditions such as connective tissue or thromboembolic disease. The current presentation discusses the epidemiology, classification, pathogenesis, and treatment of PH in the paediatric population.