We report two cases of impending paradoxical embolism through a patent foramen ovale. A 73-year-old male had recurrent pulmonary embolism and a large thrombus trapped in a patent foramen ovale. The other patient, a 70-year-old male had septic mediastinitis after prior bypass surgery and a large thrombus lodged in a patent foramen ovale. Cardiac embolectomy and closure of the foramen ovale was performed in both cases because of impending paradoxical embolism. In addition pulmonary thromboendarterectomy was performed to relieve pulmonary hypertension. Therapeutical options are discussed.