Background: Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vascular bed and causes right heart failure and death. Combination therapy which targets three different pathways is necessary due to the progressive nature of the disease. In patients with PAH, there are two approaches in combination therapy: "first-line up-front" and "sequential add-on" treatment. In "firstline up-front" treatment, patients receive double or triple drug therapy from the start. In the "sequential add-on" approach, a single drug is initially started and then according to the patient's requirements, a second or third drug is added. There is insufficient evidence about the efficiency and safety of treatment approaches. In this study, we aimed to evaluate the treatment approach in patients with PAH at a tertiary centre.