Pulmonary hypertension (PH) is a rare, incurable disease. In children, its most common form is the pulmonary arterial hypertension (PAH), caused by congenital heart diseases or occurring as the idiopathic/hereditary type. Pathological alterations are localised in peripheral pulmonary arteries and the mechanism responsible for their initiation is not entirely known. Pulmonary hypertension remains asymptomatic or oligosymptomatic for a long period of time. Its diagnosis and the determination of its aetiology require detailed diagnostically procedures, including: physical examination, transthoracic echocardiography, electrocardiography, chest X-ray, and finally, catheterisation of the “right heart” as a test necessary for the final confirmation of the diagnosis. Expanded diagnostic tests help to establish the causes of PAH. To determine the advancement stage and progress of the disease not only the clinical examination is vital, but also the results of a 6-minute walk test, echocardiography, haemodynamics and biochemical markers. Based on the advancement stage of the disease and the reactivity of pulmonary arteries, an appropriate therapeutic approach involving general guidelines, pharmacotherapy and possible interventional treatment is implemented. Currently applied pharmacotherapy does not allow the patient’s complete recuperation. However, due to the early determination of the diagnosis and faster implementation of specific therapy, the quality of life may be markedly improved. This may also decelerate the occurrence of complications, progress of the disease as well as decreased mortality. If pharmacological approach does not yield satisfactory results, palliative invasive treatment in the form of balloon atrioseptostomy or, ultimately, lung or lung and heart transplant should be considered.