We are reporting an unusual case of dural arteriovenous fistula (AVF) of the superior sagittal sinus (SSS) after tamoxifen treatment for breast cancer. A 30-year-old female arrived at the emergency room with a sudden headache and left sided weakness and sensory loss. In her past medical history, she was diagnosed with breast cancer 1 year prior, and subsequently underwent a breast conserving mastectomy with whole breast radiation and adjuvant chemotherapy with tamoxifen. At the time of admission, computed tomography showed a small acute intracerebral hemorrhage at the right parietal cortex, and magnetic resonance imaging showed that a dural AVF at the SSS with a prominent and tortuous venous enhancement along the centrum semiovale was present. Cerebral angiography showed that the dural AVF at the mid-portion of the SSS with meningeal arterial feeding vessels entering the wall of the SSS, then draining through the dilated cortical veins. Our patient had no signs of active malignancy or any abnormalities in her coagulation profile, so it can be concluded that the tamoxifen was the likely cause of the SSS thrombosis and dural AVF. The dural AVF was treated by an endovascular coil embolization for the arterialized segment of the SSS. The patient dramatically recovered favorably from left side motor and sensory deficit. The best clinical approach is to screen potential patients of tamoxifen hormonal therapy and educate them on the sign and symptoms of life threatening thromboembolic events while taking tamoxifen.