Two hypothetical birth cohorts in Bali, each consisting of 100,000 newborns, one immunized with live, attenuated JE vaccine and the other un-immunized, were modeled for JE risk over 11 years. Cumulative JE incidence before JE vaccine introduction was used to represent JE risk in the unvaccinated cohort. Data on vaccine efficacy, vaccination and treatment costs were taken from published papers and surveys. The potential immunization program averted 54 cases, 5 deaths and saved 1,224 disability adjusted life years (DALYs) at a net cost of USD 700 per JE case averted and USD 31 per DALY saved and thus was highly cost-effective.