OBJECTIVES: Gynecologic Oncology Group (GOG) 0174 compared weekly intramuscular methotrexate (MTX) with biweekly pulsed intravenous dactinomycin (Act-D) as single-agent chemotherapy for low-risk gestational trophoblastic neoplasia (GTN). Act-D had a higher rate of initial complete response (CR) (70% vs. 53%, p=0.01), but multi-day regimens of MTX have higher historic success rates. We assessed the cost-effectiveness of Act-D vs. MTX per GOG 0174 and explored multi-day MTX regimens. METHODS: A cost effectiveness decision model was constructed with data from GOG 0174. Outcome was cost per first-line treatment success expressed in terms of incremental cost-effectiveness ratio (ICER). Front-line failures were assumed to receive cross-over single agent therapy, second line failures; multi-agent chemotherapy. GOG 0174 had no quality of life (QOL) evaluation, so equal QOL (utility 1.0) was assumed but varied in sensitivity analysis. A second exploratory model included 5-day and 8-day MTX regimens. RESULTS: Act-D ($18,505) was more expensive compared to weekly MTX ($8950) with an ICER of $56,215 per first-line treatment success compared to weekly MTX. Small decreases in QOL dramatically increased the ICER during sensitivity analysis. Models with multi-day MTX regimens were also more cost-effective than Act-D. If effectiveness was redefined as avoidance of multi-agent chemotherapy, weekly MTX was more effective. CONCLUSIONS: With a complete cure rate for low-risk GTN regardless of initial agent, our model supports provider hesitation toward first line Act-D for low risk GTN. While Act-D is more effective for first line treatment success, it is more costly, and does not decrease rate of multi-agent chemotherapy use.