It is estimated that two billion people worldwide are infected with hepatitis B. In such cases, patients exposed to the virus may experience HBV-reactivation(HBVr), which is usually due to immunosuppression. It is not anticipated that spontaneous-HBVr will occur in the absence of immunosuppression in resolved HBV. In the literature, only 3 cases with spontaneous-HBVr have been reported in this setting. Our case is an 81-year-old female patient who was hospitalized for intracranial hemorrhage and spontaneous-HBVr was detected on the 24th day of hospitalization. Initially, HBsAg:(-) and anti-HBs were 77.5IU/L. Subsequent follow-up, liver function tests were increased, HBsAg:(+), anti-HBs:(-), and HBV-DNA:2513IU/ml were detected. The patient had several comorbidities such as diabetes-mellitus, hypertension, and chronic-obstructive-pulmonary-disease, but no history of immunosuppressive treatment. Following the diagnosis of spontaneous-HBVr, entecavir was initiated, resulting in the achievement of HBV-DNA negativity. It should be kept in mind that comorbidities like aging, surgery, or diabetes may trigger spontaneous-HBVr.