<h3>Purpose</h3> Operating rooms (OR) have been identified as a major source of greenhouse gas emissions in part due to their waste generation - producing an estimated 30% of hospital waste. Today, unused surgical supplies that end up in the waste system can account for 15% of total surgical supply costs. Nearly all forms of brachytherapy require use of an OR, or designated procedural suite, thus significant opportunities exist to engage staff in analyzing current practices and finding ways to reduce waste. We established a waste audit protocol to increase employee engagement and measure a single department's OR waste. <h3>Materials and Methods</h3> A three-month brachytherapy OR waste audit was conducted. The waste audit team consisted of a brachytherapy attending, two brachytherapy radiation therapists, radiation oncology residents, and a research coordinator. Standardized documents created for the audit included: a one-page waste-audit template, a one-page supply audit, and an email template sent to the brachytherapist whose cases were audited. Equipment used included a patient scale and phone camera used to document standard setup, supplies used, and waste generated. The audit was performed by an independent auditor (a resident and/or research coordinator) upon conclusion of the OR case. Procedural waste was weighed and photographed, and later analyzed collaboratively at waste audit team meetings. <h3>Results</h3> A total of 21 randomly selected HDR brachytherapy OR cases were audited between December 2021 - February 2022. The average length of time required to complete the waste audit was 6 minutes. Results were presented to all brachytherapy staff at an already established monthly meeting, and to the greater department during a five-minute time slot at the monthly departmental Quality Improvement conference. An educational poster was created depicting proper waste sorting of common OR and brachytherapy supplies into biohazard versus non-biohazard waste. All templates and education material were packaged into an public online waste audit "toolkit" which may be adapted by other departments. Further implementation of waste mitigation efforts remain underway. <h3>Conclusions</h3> The OR waste audit protocol described here serves as an efficient, feasible model that seamlessly integrates into brachytherapy practices. The standardized templates and "toolkit" may be used widely by other procedural suites, outpatient clinics, radiation oncology departments, and specialties beyond radiotherapy to evaluate current waste practices, improve care, and possibly reduce costs. Importantly, this waste audit tool serves as an easy entry point, and a call-to-action, for healthcare professionals and radiation oncologists to begin to transition to environmentally sustainable care.