Introduction: Cryptogenic stroke is present in about 40% of ischemic stroke patients. Extracardiac shunt related to pulmonary arteriovenous fistula (PAVF) could be a rare potential risk factor for embolic stroke. Most PAVFs are multiple, congenital, and associated with hereditary conditions. On the other hand, isolated PAVFs are rare conditions and an uncommon cause of cryptogenic stoke. Case Report: We describe a case of a young woman without history of respiratory diseases or vascular risk factors, who presented with acute onset of transitory aphasia and right hemiplegia. She had a history of a transient ischemic attack, 3 years before, and migraine headaches. Brain MRI showed an acute cortical ischemic lesion and a chronic ischemic lesion. Diagnostic workup with transcranial Doppler ultrasonography revealed a significant right-to-left shunt with curtain pattern, and echocardiogram did not show structural abnormalities. An isolated small PAVF was diagnosed on pulmonary angiogram. Despite the rare association between isolated small PAVF and stroke, we decided to treat it with coil embolization because of recurrence of stroke, cortical lesions suggestive of embolic source, significant right-left shunt, and risk of future complications. Conclusions: This case highlights the importance of search, identification, and interpretation of causes of cryptogenic strokes to better choose therapy to reduce the stroke recurrence risk. Although unusual, PAVF detection is a treatable cause of stroke and the therapeutic decisions should take into account the characteristics of the PAVF and the degree of suspicion regarding the cause-effect relationship between PAVF and stroke.