Purpose To determine the cost-effectiveness of olaparib, a PARP inhibitor, as maintenance therapy for platinum-sensitive (PS) recurrent ovarian cancer. Methods Two separate decision analysis models compared the cost of observation versus olaparib maintenance therapy in patients with PS recurrent ovarian cancer, one for patients with a germline BRCA1/2 mutation and one for patients with wild-type BRCA1/2. Patients received six cycles of paclitaxel and carboplatin. Drug costs were estimated using 2014–2015 wholesale acquisition costs. The cost of olaparib was estimated at $13,440 per month. Rate of germline BRCA1/2 mutation was estimated at 20%. Progression-free survival was determined from published data. Incremental cost-effectiveness ratios (ICERs) per progression-free life-year saved (PF-LYS) were calculated. A sensitivity analysis estimated the cost at which olaparib would be cost-effective. Results We estimated that there were 5549 patients diagnosed with PS recurrent ovarian cancer in the United States annually. The cost of observation in 1110 patients with a BRCA1/2 mutation was $5.5 million (M) versus $169.2 M for maintenance therapy with olaparib. The ICER for olaparib maintenance therapy in patients with a BRCA mutation was $258,864 per PF-LYS. If the cost of olaparib was decreased to $2500 per month, the ICER was $49,584. For the 4439 patients with wild-type BRCA, the cost of maintenance therapy was $444.2 M; the ICER was $600,552 per PF-LYS. Conclusions For patients with a germline BRCA1/2 mutation, maintenance therapy with olaparib is not cost-effective with an ICER of $258,864 per PF-LYS. To achieve an ICER of less than $50,000, the cost of olaparib should be $2500 or less per month. For wild-type BRCA1/2 patients, maintenance therapy with olaparib is not cost-effective.