Patent foramen ovale is widely prevalent in the normal population. Although paradoxical embolism through a patent foramen ovale has been recognized as a pathological entity since 1877, in 1988 Lechat and colleagues first sought to demonstrate an association with strokes and the presence of a patent foramen ovale. Since then, numerous retrospective, prospective, population-based, and therapeutic studies have sought to validate this association and also to demonstrate the association with other disease states such as migraine. The data from these studies are frequently conflicting, leading many authorities to even question such an association. There are ongoing randomized, double-blind, sham-treatment controlled trials for patent foramen ovale to address this controversy and determine the ideal treatment modality, if any. Dr. Ionita of the Department of Neurosciences of Catholic Health System of Buffalo provides an update on this controversial issue by reviewing the latest available literature. This clinical summary emphasizes that in young patients with cryptogenic stroke on low dose aspirin, the rate of stroke recurrence over 5-year follow-up is low and not affected by the presence or absence of patent foramen ovale; as the efficacy of percutaneous patent foramen ovale closure for secondary stroke prevention is not yet demonstrated, randomized clinical trials are ongoing. A study testing paradoxical embolism risk assessment models applicable to patients with patent foramen ovale is on the way.