Pulmonary arteriovenous malformations are direct communications between pulmonary arteries and veins via a tortuous vascular space. They can cause severe pulmonary and neurologic complications. Most PAVMs are located in the lower lobes and can be seen on radiography or angiography. However, a few patients with PAVMs have a more severe and diffuse pattern of disease. These patients generally present with more profound cyanosis and a poorer prognosis. The widespread distribution and small size of these lesions make both diagnosis and management very difficult. We report a 12-year-old patient with diffuse bilateral PAVMs confirmed by contrast echocardiography and technetium-labeled macroaggregated albumin perfusion scan.