The pulmonary angiograms of 250 patients evaluated for chronic thromboembolic pulmonary hypertension were reviewed. Pulmonary thromboendarterectomy was performed in each of these individuals, and the surgical findings were correlated with abnormal angiographic patterns. The pulmonary angiographic findings suggestive of chronic thromboembolic disease included "pouching" defects, webs or bands, intimal irregularities, abrupt vascular narrowing, and complete vascular obstruction. Pouching is reported by the authors to be a previously undescribed angiographic feature of this disease. Carefully obtained and properly interpreted pulmonary angiograms are necessary to confirm the diagnosis of operable chronic thromboembolic disease. Differential diagnostic possibilities should be considered prior to a decision to perform surgical correction.