Right hemorrhagic pleural effusion may be a presenting sign of thoracic aortic dissecting aneurysm. We describe 2 cases of massive right hemorrhagic pleural effusion and dissection of the descending aorta (type B) detected at tomographic scan. Transesophageal echocardiography ruled out a retrograde dissection of the ascending aorta. Right hemorrhagic pleural effusion is an unusual clinical presentation in thoracic aorta dissection and, up to now, the underling pathophysiology of this sign has not been defined yet.