PURPOSE Abiraterone and enzalutamide are commonly used oral cancer therapies for patients with prostate cancer, both with potentially high out-of-pocket costs for patients. We investigated the prevalence of financial assistance mechanisms used to alleviate out-of-pocket costs and the association of these mechanisms with timing of treatment initiation of abiraterone or enzalutamide. METHODS Using data from the medical center's specialty pharmacy, we identified first prescriptions for abiraterone or enzalutamide between January 1, 2017, and March 31, 2019. Prescriptions dispensed at an external pharmacy or that were discontinued for reasons unrelated to cost were excluded. Patient demographics, insurance coverage, out-of-pocket cost, and number of days between prescribed date and pill-to-mouth date were collected. RESULTS Among 220 prescriptions in our final cohort, 185 were filled through our internal specialty pharmacy, 23 through a manufacturer-sponsored patient assistance program (PAP), and 12 were never filled because of cost. One third of the prescriptions in our final cohort (n = 66) were filled with financial assistance: PAP (10%), copay cards (9%), and grants (11%). The median amount of assistance received for the first fill was $2,860 US dollars (USD) (interquartile range $1,856-$10,717 USD). Prescriptions with an out-of-pocket cost < $100 USD were filled in the shortest time (median 5 days), whereas those filled through a PAP had the longest time to initiation (median 30.5 days). CONCLUSION Among patients prescribed oral therapies for prostate cancer at a single institution, one third of patients received financial assistance. Although receiving assistance is likely to improve financial toxicity, waiting for assistance may lead to longer time to initiation of medication.