Our objective in this study was to determine the cost-effectiveness of hepatitis A vaccination strategies in healthy adults in the United States. We constructed a decision model simulating costs and health consequences for otherwise healthy adults with respect to hepatitis A prevention. Three strategies were compared: (1) no intervention, (2) vaccination against hepatitis A, and (3) testing for antibodies to hepatitis A and vaccinating those without antibodies. Costs and probabilities were obtained from the published literature. One- and two- way sensitivity analyses were performed. Under baseline conditions, the "test" strategy cost $230,100 per life-year saved compared with the "no intervention" strategy. The incremental cost-effectiveness of the "vaccination" strategy compared with the "test" strategy was $20.1 million per life-year saved. The "test" strategy was cost-effective when the hepatitis A case fatality rate exceeded 17% (baseline 2.7%). The "vaccination" strategy was cost-effective when 1 dose of vaccine cost $7 or less (baseline $57). Under baseline conditions, neither the "test" nor the "vaccination" strategies are considered cost-effective according to current standards. Large changes in hepatitis A incidence, mortality rates, or vaccine cost are required for either of the intervention strategies to approach potentially cost-effectiveness. Such conditions may occur in areas in which hepatitis A is endemic, and/or under mass-vaccination scenarios.