STUDY OBJECTIVE: Gastric cancer is the fifth most common malignancy and second leading cause of cancer-related mortality. Chemotherapy options for patients who fail first-line treatment are limited. Thus the objective of this study was to assess the cost-effectiveness of second-line treatment options for patients with advanced or metastatic gastric cancer. DESIGN: Cost-effectiveness analysis using a Markov model to compare the cost-effectiveness of six possible second-line treatment options for patients with advanced gastric cancer who have failed previous chemotherapy: irinotecan, docetaxel, paclitaxel, ramucirumab, paclitaxel plus ramucirumab, and palliative care. MEASUREMENTS AND MAIN RESULTS: The model was performed from a third-party payer's perspective to compare lifetime costs and health benefits associated with studied second-line therapies. Costs included only relevant direct medical costs. The model assumed chemotherapy cycle lengths of 30 days and a maximum number of 24 cycles. Systematic review of literature was performed to identify clinical data sources and utility and cost data. Quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs) were calculated. The primary outcome measure for this analysis was the ICER between different therapies, where the incremental cost was divided by the number of QALYs saved. The ICER was compared with a willingness-to-pay (WTP) threshold that was set at $50,000/QALY gained, and an exploratory analysis using $160,000/QALY gained was also used. The model's robustness was tested by using 1-way sensitivity analyses and a 10,000 Monte Carlo simulation probabilistic sensitivity analysis (PSA). Irinotecan had the lowest lifetime cost and was associated with a QALY gain of 0.35 year. Docetaxel, ramucirumab alone, and palliative care were dominated strategies. Paclitaxel and the combination of paclitaxel plus ramucirumab led to higher QALYs gained, at an incremental cost of $86,815 and $1,056,125 per QALY gained, respectively. Based on our prespecified WTP threshold, our base case analysis demonstrated that irinotecan alone is the most cost-effective regimen, and both paclitaxel alone and the combination of paclitaxel and ramucirumab were not cost-effective (ICER more than $50,000). Both 1-way sensitivity analyses and PSA demonstrated the model's robustness. PSA illustrated that paclitaxel plus ramucirumab was extremely unlikely to be cost-effective at a WTP threshold less than $400,000/QALY gained. CONCLUSION: Irinotecan alone appears to be the most cost-effective second-line regimen for patients with gastric cancer. Paclitaxel may be cost-effective if the WTP threshold was set at $160,000/QALY gained.