Paradoxical embolism refers to a circulatory event whereby material arising from the venous circulation passes paradoxically to the arterial circulation, as in the case of stroke, to the cerebral arterial circulation. The observation that cryptogenic stroke has in most studies been associated with an increased prevalence of patent foramen ovale (PFO) is one line of support for a model whereby a PFO is a conduit for a paradoxical thrombo embolism to the brain. Data on prothrombotic states bolster the link between deep venous thrombosis (DVT) and cryptogenic stroke. Right heart pressures often increase in parallel with pulmonary embolism, suggesting that a venous thromboembolic shower could increase the likelihood of paradoxical embolism. Warfarin is indicated only if a specific therapeutic target is present, such as a prothrombotic state, concomitant pulmonary embolism, or ischemic stroke arising from a DVT passing through a PFO as a paradoxical embolism on a probable basis.