Problem: Pediatric oncology patients are at a high risk for acquiring vaccine-preventable diseases due to their previous immunocompromised status and loss of protective titers following chemotherapy treatment. According to a nationwide study in 2019, only 48% of providers assess immune status prior to revaccination and re-vaccination time frame ranges from 6-18 months. This inconsistency is mirrored within an urban pediatric oncology clinic, leading to children with unnecessary and prolonged vulnerability to vaccine-preventable diseases. Purpose: The purpose of this quality improvement project was to implement an evidence-based standard of practice for re-immunization of pediatric oncology patients following completion of chemotherapy treatment. Methods: The project was implemented over a 16-week period in a pediatric oncology clinic. Eligible patients included those diagnosed with cancer since 2013 and off chemotherapy treatment for at least 6 months. The new standard of practice included a formal guideline detailing the vaccine titers to be obtained based on current evidence. A template was created and inputted into the patient’s problem list. A standardized letter was sent to each patient’s primary care provider detailing the patient’s individualized vaccination plan. Weekly chart audits were conducted and run charts created to track data. Results: Results of the intervention demonstrated 83% of eligible patients had required titer orders and had the need for immunization added into their problem list. 50% of patients had fully resulted titers. Of the 50%, 100% demonstrated loss of immunity to one or more vaccine preventable diseases. Several confounding factors delayed results of titers and communication with primary care providers such as insufficient blood quantity and hemolyzed samples leading to partially resulted titers. Pediatric oncology providers sought to send one letter to the patient’s primary care provider detailing comprehensive immunization recommendations following fully resulted titers. Conclusions: This quality improvement project demonstrated the need for immunization assessment and intervention following treatment with chemotherapy. Creation of a standard post-chemotherapy vaccination guideline improved the identification and re-immunization of this population.