OBJECTIVES: To develop a costing exercise that allows comparing the direct costs in each functional class (FC) I to IV, of Pulmonary Arterial Hypertension (PAH) from perspective of the third-party-payer. METHODS:  PAH is a disease with a very low prevalence in Colombia, high rate mortality and deterioration in HRQoL, make it to be considered an orphan disease. The treatment cost of a patient with PAH varies considerably according to the disease progression, mainly influenced by the hospital and pharmacological costs that it requires. Treatment cost for patient during a year of staging in each FC of the disease were estimated, according to WHO classification, pharmacological costs for each stage were included taking into account the clinical recommendations observed in the SEPAR-ALAT2 guide. A literature review was carried out to compare information in treatment scheme necessary for the patient, including the procedures, this information was validated with experts. Costs of the resources and inputs were taken from SOAT 2001 +30 tariff, and from market drugs. RESULTS: Results are presented as the consolidated of direct costs that could be required by a patient over a year of treatment, these costs include outpatient, hospital management, medication support, and medical consultations required, the exercise allows to evidence a high cost in FC IV, this being US $ 7,189 per month, while in FC-II and III costs are US $ 2,950 and US $ 2,918 per month respectively, a patient in FC-I would represent a cost of US $ 294 per month. CONCLUSIONS:  The results of the exercise demonstrate the need to concentrate the focus of patient care, to avoid its progression, since a patient progressing to FC IV represents a high considerable cost to health system. In addition to this, the progressing patient represents a higher occupation of hospital resources, which also implies a considerable deterioration in HRQoL.