Patent foramen ovale (PFO) is present in 25-30% of the population. Spontaneously, or with activities implying a Valsalva maneuver, a transient right-to-left shunt occurs. This can now be easily diagnosed with contrast echography. We report 29 cases of paradoxical cerebral embolism with a PFO and compare them with 25 reported cases. There may be clinical evidence suggesting the diagnosis: a Valsalva-inducing activity at the onset of stroke. previous chronic pulmonary hypertension, contemporary pulmonary embolism and evidence of deep vein thrombosis.