Pulmonary capillary hemangiomatosis (PCH) is a rare cause of primary pulmonary hypertension characterized by thin-walled microvessels infiltrating the peribronchial and perivascular interstitium, the lung parenchyma, and the pleura. These proliferating microvessels are prone to bleeding, resulting in accumulation of hemosiderin-laden macrophages in alveolar spaces. Here we report 2 cases of PCH with pulmonary hypertension, 1 of them associated with mechanical intravascular hemolysis, a feature previously reported in other hemangiomatous diseases, but not in PCH. Case 2 was diagnosed by pulmonary biopsy; to our knowledge the patient is the second adult to be treated with interferon alpha-2a. Review of the literature identified 35 patients with PCH and pulmonary hypertension. The prognosis is poor and median survival was 3 years from the first clinical manifestation. Dyspnea and right heart failure are the most common findings of the disease. Hemoptysis, pleural effusion, acropachy, and signs of pulmonary capillary hypertension are less common. Chest X-ray or computed tomography scan usually shows evidence of interstitial infiltrates, pulmonary nodules, or pleural effusion. Hemodynamic features include normal wedge pressures. Radiologic and hemodynamic findings are undifferentiated from those of pulmonary veno-occlusive disease but differ from other causes of primary pulmonary hypertension. Epoprostenol therapy, considered the treatment of choice in patients with primary pulmonary hypertension, may produce pulmonary edema and is contraindicated in patients with PCH. Regression of lesions was reported in 1 patient treated with interferon therapy and 2 other patients stabilized, including our second patient. PCH was treated successfully by lung transplantation in 5 cases. Early recognition of PCH in patients with suspected primary pulmonary hypertension is possible based on clinical and radiologic characteristics. Diagnosis by pulmonary biopsy is essential for allowing appropriate treatment.