Background: Chemotherapy is a risk factor for HBV reactivation in pts with cancer and chronic HBV. Anti-viral prophylaxis can prevent reactivation but requires identification of infected pts. Many guidelines recommend universal HBV screening prior to cytotoxic/immunosuppressive-therapy, but lack of screening is common globally. A serious safety event and high prevalence of pts from HBV endemic regions receiving treatment at our institution led to a quality improvement project to increase HBV screening prior to chemotherapy. We aimed to increase HBV screening in pts starting systemic therapy at Princess Margaret by 100% by February 28, 2019. Methods: Starting April 2017, an interrupted time series study was undertaken. Baseline HBV screening rate was 43%. Diagnostics including interviews, process mapping and root cause analysis were performed. Interventions to address identified root causes were implemented including specifying required HBV tests, tips for ordering HBV tests, provision of electronic Hepatology referral form, a safety alert email, grand rounds presentation of serious safety event, including HBV screening rate in departmental monthly quality emails and Divisional meetings and adding positive HBV results to the laboratory alerting system. The main outcome measure was the proportion of pts starting systemic therapy screened for HBV. Process measures included correct test ordering, number of Hepatology referrals was a balancing measure. Results were analysed with statistical process control charts. Results: From April 2017-Feb 2019, 5604 pts commenced systemic therapy. Interventions were modified iteratively as the project progressed. HBV screening rate improved from 43 to 79% (84% improvement). Incidence of chronic HBV was routinely above the Canadian average ( > 2%). The percent of correctly ordered screening tests fell from 48 to 33% (31% worsening), while the volume of Hepatology referrals remained manageable (1.5 pts/week). Conclusions: Our Quality Improvement project led to a significant improvement in HBV screening prior to systemic therapy. Further interventions are planned to achieve our target improvement of 100%.