Background: ASCO strongly endorses the integration of palliative care to improve patient outcomes and support patients in their cancer trajectories. Developing core palliative care skills for trainees is therefore essential, with few ACGME approved pilot programs offering combined fellowship training. Our institution’s Heme/Onc fellows reported a need for additional education in leading difficult conversations. Methods: We piloted a didactic simulation (sim) session for each fellowship class, led by a faculty member who is dual board-certified in Medical Oncology and Hospice/Palliative Medicine. Trainees received a lecture on validated communication tools and oncology-specific language to help navigate difficult conversations. Trainees then role-played in small groups using sample cases, with Heme/Onc faculty supervision and real-time feedback, followed by class reflection. Pre- and post-sim surveys were electronically administered to assess knowledge of communication tools and comfort in discussing difficult topics. Comfort questions were scored on a 5-point Likert Scale, using student t-tests to detect differences pre- and post-sim, and ANOVA to compare responses among classes. Results: A total of 16/21 (76.2%) fellows completed both pre- and post-sim surveys. Knowledge of communication tools increased from 21.9% pre-sim to 79.7% post-sim. Comfort significantly increased for explaining palliative-intent chemotherapy, hospice, and discussing an uncertain prognosis (Table). There was a significant difference among classes pre-sim for addressing negative emotions (mean comfort level: 1^st years 2.8, 2^nd years 3.4, 3^rd years 3.83; p=0.046) and for discussing an uncertain prognosis (mean comfort level: 1^st years 2.6, 2^nd years 3.6, 3^rd years 3.83; p=0.043); however, these interclass discrepancies were eliminated post-sim. Overall, fellows reported that the sim sessions were effective for developing their knowledge and comfort in having difficult conversations. Conclusions: A novel sim intervention led by a physician who is dual board-certified in palliative care and medical oncology improves trainee competency with navigating difficult conversations. Analysis of the intervention’s durability of response and iterative refinement of its curriculum are ongoing.