OBJECTIVE: We sought to estimate mean costs of chemotherapy treatment for recurrent ovarian cancer with or without use of a chemoresponse assay. STUDY DESIGN: We estimated mean costs for 3 groups: (1) assay assisted: 75 women who received oncologist's choice of chemotherapy following chemoresponse testing (65% adherence to test results), (2) assay adherent: modeled group assuming 100% adherence to assay results, and (3) empiric: modeled from market share data on most frequently utilized chemotherapy regimens. Cost estimates were based on commercial claims database reimbursements. RESULTS: The most common chemotherapy regimens used were topotecan, doxorubicin, and carboplatin/paclitaxel. Mean chemotherapy costs for 6 cycles were $48,758 (empiric), $33,187 (assay assisted), and $23,986 (assay adherent). The cost savings related to the assay were associated with a shift from higher- to lower-cost chemotherapy regimens and lower use of supportive drugs such as hematopoiesis-stimulating agents. CONCLUSION: Assay-assisted chemotherapy for recurrent ovarian cancer may result in reduced costs compared to empiric therapy.