Pulmonary artery pseudoaneurysm is a well-recognized and potentially lethal complication of pulmonary artery catheterization. A surgical or interventional radiologic approach has been advocated as the treatment of first choice. A pulmonary artery pseudoaneurysm developed in 70-year-old woman after the insertion of a Swan-Ganz catheter for an abdominal aortic aneurysm. Over a 4-month period the pseudoaneurysm regressed and disappeared radiologically. This represents the first report of such an occurrence. The radiographic findings and review of the literature are discussed.