Introduction: Advances in the medical care for oncology patients has heightened the complexity of this patient population leading to an increased need for lifesaving, critical care. Oncology nurses provide specialized nursing care; however, when patients require lifesaving care, they are transferred to critical care units. The project oncology unit opened high acuity beds to prevent the need to transfer these patients. The purpose of this scholarly project was to evaluate oncology nurses’ mastery of basic and oncology-specific critical care knowledge following an evidence-based supplemental training course. Methods: This quality-improvement project used Basic Knowledge Assessment Tool (BKAT) results to evaluate oncology nurses’ critical care knowledge after an initial 3-month education course. Supplemental training content was developed using the score deficiencies noted. Content on oncology-specific critical care was also developed. BKAT and Oncology Knowledge Survey scores were evaluated pre-and post-supplemental training and Wilcoxon signed rank tests were used to detect significant changes. Results: Seventeen nurses completed the 8-hour supplemental training. Mean total BKAT scores significantly improved from 65.7 pre-initial course to 73.7 post-supplemental training (p=0.002). Mean total Oncology Knowledge Survey scores increased from 75.3% to 80.9%, which was a statistically significant improvement (p=0.039). Conclusion: Critical care training is imperative for oncology nurses preparing to care for high acuity oncology patients. Having adequate knowledge of general and oncology-specific critical care is important to prevent adverse events among this complex patient population and to improve overall outcomes.