Objective: To evaluate total and out-of-pocket costs for poly(ADP-ribose) polymerase (PARP) inhibitors and differences based on insurance characteristics. Methods: We identified ovarian cancer patients who were prescribed niraparib, olaparib, or rucaparib from the MarketScan (2014–2017) and Surveillance, Epidemiology, and End Results (SEER)-Medicare (2014–2016) databases. Drug costs were estimated for a 30-day supply. Descriptive statistics and Wilcoxon rank sum tests were performed. Results: 590 commercially insured beneficiaries from MarketScan and 213 SEER-Medicare beneficiaries were prescribed PARP inhibitors for a median 112 days. For commercially insured beneficiaries, median total cost was $13,342 (IQR $12,022–$14,256). Median out-of-pocket cost was $44 (IQR $0–$120) and PARP inhibitors accounted for a median 90.8% of patients' total out-of-pocket drug spending. High-deductible health plan was not associated with higher out-of-pocket costs (N = 570; median $0 vs. $45, P = 0.87). For SEER-Medicare beneficiaries, median total cost was $12,798 (IQR $11,704–$13,180). Median out-of-pocket cost was $370 (IQR $2–$1234) and PARP inhibitors accounted for a median 99.0% of patients' total out-of-pocket drug spending. Out-of-pocket costs were lower for dual-eligible patients with supplemental Medicaid prescription coverage (N = 209; median $1 vs. $911, P < 0.001). Conclusions: Although insurers are responsible for a large proportion of PARP inhibitor costs, out-of-pocket costs for PARP inhibitors account for a majority of patients' drug spending. SEER-Medicare beneficiaries had higher out-of-pocket costs than patients with commercial insurance, which was offset for those with supplemental Medicaid prescription coverage.