Background OCCULT HEPATITIS B infection (OBI) is considered a risk factor for progression of liver disease in patients with HEPATITIS B virus (HBV) infection. This disease progression is reported to be more significant in those with concomitant HIV infection. We aimed to determine the prevalence rate of OBI in a sample of HIV-positive patients. Materials and Methods: Sixty-six HIV-infected patients with positive HEPATITIS B core antigen (HBcAb) and negative HEPATITIS B surface antigen HBsAg were included. HBV DNA was measured by real time polymerase chain reaction PCR method. Those with positive HBV viral load were considered as seropositive OBI. Then, the patients were studied regarding age, gender, intravenous drug use (IVDU), CD4 count, and concomitant infection by HEPATITIS C virus (HCV), available in their medical records. Results: Seventy-seven patients (38. 5%) had positive HBc antibody (HBcAb). Of 66 patients who were positive for both HIV and HBc antibody, eight patients (12. 12%) had OBI. About 3. 7% in age group younger than 40 years and 5. 3% in age group older than 40 years, OBI was detected. Forty-four patients (54. 5%) were male. OBI rate was 22. 2% in males and zero in females (P< 0. 05). In patients who received ART (anti-retroviral therapy) 11. 3% and in those who did not receive ART, 12. 4% had OBI. In patients with CD4 count of less than 350/mL, 20. 1% and in those with CD4 count > 350/mL, 4. 1% had OBI. In those who were IV drug user, 17. 94% and in those who were not IV drug user, 3. 57% gad OBI. Conclusion The prevalence of OBI in the studied sample of HIV-infected patients is considerable. As we did not find any significant association between OBI and studied factors except for gender, we think that screening for OBI would be useful for HIV-infected patients, especially male patients.