In 2015, the Defense Health Agency (DHA) initiated the transition from a legacy Electronic Health Record (EHR) system to a commercial product (Oracle Cerner, further referred to as “MHS Genesis”). DHA transitioned sixteen Military Treatment Facilities (MTFs) that provide Oncology services to the MHS Genesis system over a period of five years. Updates in the vendor oncology package that were implemented later in the deployment process resulted in inconsistencies in configuration and a lack of standardized workflows across the facilities. In addition, earlier facilities implemented a less mature system where chemotherapy orders were entered using traditional order sets, requiring repeat order entry with each patient visit. This caused increased clinician burden and fragmented patient data, resulting in workarounds, decreased productivity and low clinician and staff satisfaction. To address these issues, the Oncology Clinical Community, in collaboration with DHA-Health Informatics, created a multi-pronged approach aimed at developing and implementing optimized, standardized workflows. An updated chemotherapy regimen library was created based on the National Comprehensive Cancer Network guidelines, enabling safer, more streamlined chemotherapy ordering and decreased use of standard order sets over time. A comprehensive training plan was implemented to ensure appropriate use of chemotherapy regimens and adoption of consistent workflows across all sixteen facilities. Additionally, the team developed an improved tracking system to manage requested configuration changes and updates to chemotherapy regimens to ensure system sustainment and manage maintenance over time. All regimens are approved by the Oncology Clinical Community before moving into production. Comprehensive workflows were developed to identify an end-to-end process for chemotherapy ordering, verification, modification, and administration. Following Oncology Clinical Community leadership approval, the workflows were introduced through a multi-disciplinary summit where end-user feedback was solicited. The training plan was introduced at a pilot site and refined before implementation across the facilities. Full training across the sixteen MTFs is expected to be complete by 12/2023. The team built a total of 756 regimens. Of these, 356 have been clinically reviewed and approved. A process is in place to manage needed updates, including clinical review in a timely manner. Thirteen of the sixteen facilities adopted the standardized workflows with positive initial feedback. Over a 4-month period from March to June 2023, the use of standard order sets for chemotherapy decreased by approximately 60%, with regimen use increasing as they are built, approved, and released to production. A follow-up user satisfaction survey was distributed following training at each site. Results are currently under review. Future work will focus on ongoing maintenance of the chemotherapy regimen library, full implementation of a Pediatric Chemotherapy regimen library, optimized Bone Marrow Transplant workflows and continued monitoring of user satisfaction, regimen adoption, and patient safety across the MTFs.