Background: High healthcare costs can pose a barrier to access and contribute to financial hardship among patients with cancer. Charitable co-pay assistance (CPA) foundations provide financial support to patients facing high out-of-pocket costs, but little is known about the sociodemographic characteristics, financial burdens, views and experience of those receiving assistance. Methods: We conducted a national, cross-sectional survey of CPA grant recipients receiving financial assistance from the HealthWell Foundation (charitable CPA foundation) to cover cancer drug costs. The primary outcome of interest was self-reported financial distress (FACIT-COST). Secondary outcomes included measures of out-of-pocket spending, patient perspectives on CPA support, healthcare access and costs, and the impact of financial burden on healthcare utilization. Results: Among 1,108 CPA grant recipients, over 20 cancer types were represented, including 30% with solid tumors and 70% hematologic malignancy. Average age of CPA recipients was 72 (range: 41-92), 60% were male, 88% white, 55% college educated, and 67% had annual income < $60,000. 96% had Medicare (53% Traditional, 43% Advantage, 58% with supplemental insurance), and 66% believed insurance would prevent them from paying high drug costs. However, 54% reported spending > $500 per month on healthcare, with 39% spending > 10% of household income. Among 17% reporting delays in starting therapy due to cost, 28% reported delay > 4 weeks. Overall, 18% reported skipping medical services due to cost, and 24% believed they would not have received their treatment without CPA. On the COST scale, 56% reported mild financial toxicity (COST 14-25) and 27% moderate/severe (COST < 14) despite CPA. In bivariate analysis, younger age, solid tumor, lower income, female gender, higher anxiety and depression (PHQ4), greater comorbidity, and traditional Medicare were all significantly associated with greater financial distress (lower COST scores, P < 0.05 for all). Most (76%) CPA recipients believed that doctors should be aware of costs when making decisions, and 91% supported Medicare negotiating drug prices with manufacturers. With regard to why they required CPA, only 6% attributed it to failure to discuss costs with their doctor, 14% to the healthcare system, 51% to poor insurance coverage, 61% to their financial status, and 82% to high drug costs. Notably, 73% reported a decrease in financial concerns as a result of CPA. Conclusions: In this large national sample of CPA grant recipients with cancer, most had Medicare and believed insurance would shield them from high drug costs, yet many reported delays in starting therapy prior to CPA and ongoing financial distress. CPA may play an important role in securing access to therapy but these findings highlight an ongoing need to address financial toxicity and understand potential disparities in access to CPA.