The aim of this systematic review is to describe the main characteristics of pulmonary hypertension in childhood. This disease is defined as increased pressure and vascular resistance in pulmonary circulation. Etiology, clinical presentation, latest classification, and modern-used diagnostic and therapeutic methods are described in this thesis. Pulmonary hypertension covers a wide range of diseases with numerous and often unknown causes. During the course of time, the classification has changed a few times, and according to that latest one which was established in Nice in 2013, pulmonary hypertension can be divided into 5 large groups: pulmonary arterial hypertension, pulmonary hypertension due to left heart disease, pulmonary hypertension due to lung diseases and/or hypoxia, chronic thromboembolic pulmonary hypertension, and pulmonary hypertension with unclear multifactorial mechanisms. Despite the great advances that have been made in diagnostics and therapy, the success of the applied therapy depends on whether or not the cause had been defined, and due to this fact, the diagnostic methods are complex and comprehensive. During the last two decades, it still remains an important factor of morbidity and mortality. Groups of medicines described in this thesis which are used in treatment include calcium channel blockers, prostaglandin analogs, endothelin receptor antagonists, and phosphodiesterase inhibitors. In certain cases, depending on the cause, surgical procedure can be an option.