<i>Background:</i> Pulmonary hypertension (PH) is a severe hemodynamic disorder in which the pulmonary artery pressure is persistently elevated, leading to right-sided heart failure. Some studies have suggested an association between PH and myeloproliferative diseases (MPD). <i>Objectives:</i> This study describes clinical, hematological and hemodynamic characteristics of PH associated with MPD. <i>Methods:</i> We retrospectively reviewed 10 cases of PH associated with MPD: polycythemia vera (8 patients) and essential thrombocythemia (2 patients), followed between 1993 and 2002. The baseline evaluation was established by right-sided heart catheterization, ventilation/perfusion lung scan and pulmonary angiography if required. <i>Results:</i> Six patients had confirmed chronic thromboembolic pulmonary hypertension (CTEPH) and 4 had pulmonary arterial hypertension (PAH) associated with MPD without other risk factors for PAH. The hemodynamic characteristics of CTEPH and PAH associated with MPD were similar. The diagnosis of CTEPH was concomitant to that of MPD in all cases (5 polycythemia vera and 1 essential thrombocythemia). The PAH associated with MPD occurred later in the evolution of the MPD (3 polycythemia vera and 1 essential thrombocythemia) with a median of 162 months after the diagnosis of MPD, and it was associated with myeloid metaplasia (p < 0.01). <i>Conclusion:</i> We describe 2 distinct forms of PH in the context of MPD: CTEPH, which is diagnosed at an early stage of the MPD, and PAH, which occurs later in the course of the MPD and is associated with myeloid metaplasia. Progressively increasing dyspnea in a patient with an MPD warrants further investigation to rule out PAH and CTEPH, while a diagnosis of CTEPH warrants ruling out MPD.