SEVERITY AND TREATMENT: The management of primitive pulmonary hypertension starts by the evaluation of its severity, based on the New York Heart Association's (NYHA) functional classification and right cardiac catheterization data. Hemodynamic criteria of poor prognosis are: an increase in right atrial pressure > 10 mm Hg, a decrease in cardiac output (cardiac index < 2.2 l/min/m2), an increase in pulmonary vascular resistance > to 20 mm Hg/l/min/m2, and saturation of the oxygen content in venous blood < 63%. These prognostic data will condition treatment. CALCIUM CHANNEL BLOCKERS: Are the only vasodilators that have demonstrated efficacy in primitive pulmonary hypertension (PPH). However, only 20% of patients respond to calcium blockers. To determine a positive response to these agents, a carbon monoxide inhalation test is required during right cardiac catheterization. Prescription of calcium channel blockers to non-responders is often responsible for adverse events, from enhanced dyspnoea to sudden death. Continuous intravenous infusion of epoprostenol has considerably improved the prognosis of PPH and related pulmonary hypertension (PH). Despite the constraints, such treatment should be proposed to NYHA functional class III and IV patients not responding to carbon monoxide tests, until new, equally efficient products have been launched on the market. If epoprostenol fails or provokes severe side effects, pulmonary or cardio-pulmonary transplantation should be envisaged.