Failures and complications were analyzed retrospectively in 45 patients treated with embolotherapy or occlusion of pulmonary arterial circulation. Pulmonary arterial branches were occluded with steel coils in 19 patients with pulmonary arteriovenous malformations, 17 with hemoptysis of pulmonary artery (PA) origin, and one with massive parenchymal shunt. Bronchial arterial supply to the lung was embolized with small particles in eight cases of hemoptysis and systemic to pulmonary arterial antegrade shunt secondary to chronic thromboembolism. Asymptomatic incidents included catheterization failures, vascular damage, partial occlusion, partial recanalization of the thrombus, ectopic deposition of a coil, and delayed bacterial contamination of the thrombus. A few cases of transient clinical and radiologic signs of pulmonary infarction were observed after complete occlusion of the PA and bronchial artery embolization. This complication was never observed after complete occlusion of main right or left PA, inferior right or left PA, or segmental branches. The management and prevention of these complications, the role of bronchial arterial collateral pathways, and the importance of the site of PA occlusion in the development of pulmonary infarction are discussed.