Background: Numerous oral anticancer drugs approved for metastatic prostate cancer are expensive and put patients at risk for financial toxicity. Mechanisms available to mitigate these costs are complex to navigate. Furthermore, the ability to access these resources may not be the same for every insurance. We examined the out-of-pocket (OOP) liability of patients prescribed abiraterone or enzalutamide, the assistance mechanisms used, and the impact on timing of therapy. Methods: Patients with prostate cancer who were prescribed abiraterone or enzalutamide at our comprehensive cancer center between January 1, 2017 and March 31, 2019 were identified. Patients who filled prescriptions via an external pharmacy were excluded. Data regarding demographics, out of pocket costs and assistance mechanisms were evaluated. Results: We identified 219 patients. Of these, 33% had commercial insurance, 61% had Medicare part D, 3% had Medicaid and 8% had no insurance. Most patients (74%) were prescribed abiraterone and 26% enzalutamide. Among those with Medicare Part D, almost one third received significant financial assistance: 11% free drug from the manufacturer and 18% foundational grants. Patients with commercial insurance received a copay card from manufacturers 21% of the time. Patients with commercial insurance paid an average of $57 OOP; 94% with initial cost < $100. Patients with Medicare part D paid an average of $582 OOP; 22% with initial cost > $1000. Commercially insured patients started treatments in under 10 days from the prescription date 51% of the time vs 39% for Medicare patients. In contrast, 11% of commercially insured patients required > 30 days to fill vs 19% on Medicare. Only 1% of commercially insured patients were unable to fill due to cost issues compared to 7% of patients on Medicare. Conclusions: Financial assistance mechanisms such as grants and free drug programs help alleviate some financial burden for patients, but many still experience high OOP costs. These burdens appear to be disproportionately experienced by patients with Medicare Part D. We observed that patients with Medicare Part D had higher OOP costs for oral prostate cancer therapies. Those who required assistance often experienced delays in obtaining medication. Further evaluation is planned into how high costs and delays in treatment impacts prostate cancer treatment and patient care.