Background: Clinical trials are critical for improving outcomes for patients with cancer. However, there is some concern from health insurers that clinical trial participation can increase total cost of care for cancer patients. We investigated the impact of clinical trial participation on total costs paid by Medicare during the OCM program in a large community-based practice. Methods: Tennessee Oncology (TO) is a community oncology practice comprising over 90 oncologists across 30 sites of care. We linked TO trial data and electronic medical record data with OCM data for episodes of care from 2016-2018. To assess the impact of trial participation on total cost relative to routine care, we created matched comparator groups for each OCM episode based on cancer type, metastatic status, number of comorbidities, performance status, and age. Patients with breast cancer receiving hormone therapy only were excluded. Absolute and percent cost differences between groups were calculated for episodes that had a comparator group size of five or greater. Differences in total cost for trial episodes were compared to non-trial episodes, and significance was assessed using the Mann–Whitney U test. We also studied the impact of trial participation on receipt of active treatment in the last 14 days of life (TxEOL), hospice use, and hospitalizations. Results: During the study period, 8,026 completed OCM episodes met study criteria. Patients were enrolled in a clinical trial for 459 of these episodes. On average, episodes during which patients were on trial cost $5,973 less than matched non-trial episodes (Table), independent of early versus late-phase trial. Most savings resulted from decreased drug costs. There were no differences in rates of TxEOL (15% vs. 14% p=1.0), rates of hospitalizations (31% vs. 30% p=0.54), or hospice use (52% vs. 62% p=0.08) between trial and non-trial episodes. Median difference from comparator group average cost was significantly lower for clinical trial episodes (-18% vs. -6%, p<0.01). Conclusions: In the community setting, total costs paid by Medicare for patients participating in clinical trials during OCM episodes were lower than costs for similar patients receiving routine care. Clinical trial participation did not adversely impact end-of-life care or likelihood of hospitalization. These findings suggest that patient participation in clinical trials does not increase total cost of care nor enhance financial risk to payers.