Background Chronic infection with hepatitis C virus (HCV) genotype 2 or 3 can be treated with sofosbuvir without interferon. Because sofosbuvir is costly, its benefits should be compared with the additional resources used. Objective To estimate the cost-effectiveness of sofosbuvir-based treatments for HCV genotype 2 or 3 infection in the United States. Design Monte Carlo simulation, including deterministic and probabilistic sensitivity analyses. Data Sources Randomized trials, observational cohorts, and national health care spending surveys. Target Population 8 patient types defined by HCV genotype (2 vs. 3), treatment history (naive vs. experienced), and cirrhosis status (noncirrhotic vs. cirrhotic). Time Horizon Lifetime. Perspective Payer. Intervention Sofosbuvir-based therapies, pegylated interferon–ribavirin, and no therapy. Outcome Measures Discounted quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs). Results of Base-Case Analysis The ICER of sofosbuvir-based treatment was less than $100 000 per QALY in cirrhotic patients (genotype 2 or 3 and treatment-naive or treatment-experienced) and in treatment-experienced noncirrhotic patients but was greater than $200 000 per QALY in treatment-naive noncirrhotic patients. Results of Sensitivity Analysis The ICER of sofosbuvir-based therapy for treatment-naive noncirrhotic patients with genotype 2 or 3 infection was less than $100 000 per QALY when the cost of sofosbuvir was reduced by approximately 40% and 60%, respectively. In probabilistic sensitivity analyses, cost-effectiveness conclusions were robust to uncertainty in treatment efficacy. Limitation The analysis did not consider possible benefits of preventing HCV transmission. Conclusion Sofosbuvir provides good value for money for treatment-experienced patients with HCV genotype 2 or 3 infection and those with cirrhosis. At their current cost, sofosbuvir-based regimens for treatment-naive noncirrhotic patients exceed willingness-to-pay thresholds commonly cited in the United States. Primary Funding Source National Institute on Drug Abuse and National Institute of Allergy and Infectious Diseases.