Acute hepatitis A is a major public health problem in developed countries, and because a large proportion of patients with acute hepatitis A do not have any identifiable risk factors, current practice of targeting the high-risk groups for vaccination against hepatitis A virus (HAV) is unlikely to have a significant impact on the overall incidence of acute hepatitis A. No economic analysis of strategies of mass immunization against HAV is available. Three different strategies of immunization against HAV using commercially available inactivated vaccine were compared in a Markov model analysis of a cohort of 2-year-old healthy children in a developed country. In strategy I, universal vaccination was pursued. In strategy II, children were initially screened for antibody and, if susceptible, they were vaccinated. In strategy III, no vaccination was offered. Cost per person and quality adjusted life-years (QALY) gained in each strategy were the outcome measures compared. The baseline analysis showed that strategy II is more cost-effective than strategy I, with marginal cost-effectiveness ratios of $7,267. 67 and $12,833.34, respectively, compared with a strategy of no intervention. Sensitivity analysis showed that if the cost of the two-dose vaccine could be reduced to less than $57, the strategy of universal vaccination would be the preferred immunization strategy. Different strategies of mass immunization against HAV in the developed countries are cost-effective by current standards of health care interventions and should be considered for incorporation into current childhood immunization programs.