A patent foramen ovale has been reported to be more frequently detected in cryptogenic stroke, with paradoxical embolism as the major pathogenetic mechanism. The standard procedure for the detection of a patent foramen ovale is transesophageal echocardiography. Transcranial Doppler sonography with bubble test is almost as reliable as transesophageal echocardiography. Seventeen patients with acute ischemic stroke and transient ischemic attacks hospitalized at the Department of Neurology in Novi Sad underwent examinations to detect a patent foramen ovale, which was found in 55.6% of patients with cryptogenic stroke. The average age of these patients was 30.6 years. Transcranial Doppler sonography showed 100% sensitivity and 100% specificity for the prediction of right-to-left shunts proven by transesophageal contrast echocardiography. Both positive and negative predictive values in our group of patients were 1. Transcranial Doppler with bubble test is a reliable method for the detection of a patent foramen ovale, with a high level of sensitivity and specificity which is comparable with transesophageal echocardiography. Moreover, it is cheaper and more comfortable than transesophageal echocardiography, and should be used routinely in neurological practice.