Idiopathic pulmonary arterial hypertension is a rare and potentially fatal condition. Without treatment, survival is only approximately 2.8 years from diagnosis. However, if the pulmonary hypertension is secondary to other causes, especially to congenital heart disease, it is possible to survive for 30 years or more without treatment. In recent years, remarkable progress has been made, risk factors have been identified and improved imaging techniques, including echocardiography, computer tomography and magnetic resonance imaging, are available. The condition can affect children at any age from fetal life through to adulthood. Patients can present to the respiratory pediatrician with unresponsive asthma, to the neurologist with faints or to the general pediatrician with failure to thrive. Over the last few years there have been significant developments in the available therapy for managing this complicated disease, which have improved the prognostic outlook, such as oral bosentan and sildenafil, intravenous epoprostenol and interventional catheterization with atrial septostomy. This article reviews the current knowledge about causation, investigation and treatment of children with pulmonary hypertension in the clinical setting.