Diagnosis of cerebral sinus venous thrombosis (CSVT) requires high index of suspicion owing to the varied spectrum of its clinical manifestations. Its diagnosis may be more elusive if the patient presents with subarachnoid hemorrhage (SAH). We report a case of CSVT that presented with SAH without underlying parenchymal involvement and will elaborate the importance of the early diagnosis of CSVT. Twenty-three years old woman presented with thunderclap headache and neuroimaging initially suggested SAH with no associated parenchymal bleeding. SAH involved the sulci of the convexity and spared the basal cisterns. Angiography revealed occlusion of intracranial venous sinuses without revealing any other cause of SAH. She showed marked improvement with anticoagulant therapy. In our observation, isolated CSVT can present solely as unilateral, localized SAH at the convexity without underlying parenchymal involvement. Because other causes of nontraumatic SAH do not frequently present in this manner, identification of this unusual imaging appearance should prompt strong consideration of the diagnosis of cortical sinus venous thrombosis.