Background: Hepatitis B (HBV) can lead to clinical hepatitis, fulminant liver failure and cirrhosis in patients (pts) receiving immunosuppressive therapy (IST). The American Society of Clinical Oncology and other guidelines recommend screening cancer pts for chronic HBV if at high risk for infection or if anticipating highly IST such as stem cell transplant (SCT) or rituximab. It is recommended that patients who screen positive should be treated with antiviral prophylaxis (ppx) to decrease the risk of viral reactivation. In this study, we determine how these guidelines have impacted clinical practice. Methods: We performed a retrospective single center analysis of pts with hematologic malignancies who underwent intrathecal chemotherapy from 2010-2016. We collected data on HBV screening with either Hepatitis B surface antigen (HBsAg) or Hepatitis B core antibody (HBcAb) along with rates of antiviral prophylaxis and HBV reactivation. Results: In total, 170 pts were included of which 119 (70%) received HBV screening (114 tested for HBsAg, 84 tested for HBcAB). Eleven pts (9.2%) had a positive screening test within 1 year of chemotherapy and 8 (73%) of them were treated prophylactically. Two additional pts were found to be positive for HBcAb while on chemotherapy and neither received ppx. In total, 5 of 13 pts (38%) with positive tests for HBV did not receive ppx despite the fact that 4 of 5 (80%) were treated with either SCT or rituximab. There was one case of HBV reactivation which occurred in a patient who screened positive, was placed on ppx, but who developed an asymptomatic 2 log rise in HBV DNA and mild transaminitis 7 months into chemotherapy due to medication non-adherence. Viral ppx was resumed, HBV viral load decreased and the transaminitis resolved. Conclusions: In patient with hematological malignancies at a large academic medical center, there was significant variability in screening and prophylactic treatment of HBV. This can lead to poor patient outcomes which are avoidable and we are implementing a quality improvement project to streamline and improve this process.