Objective: This study aims to assess the cost-effectiveness of rotavirus immunization in Indonesia, taking breastfeeding patterns explicitly into account. Method: An age-structured cohort model was developed for the 2011 Indonesia birth cohort. Next, we compared two strategies, the current situation without rotavirus immunization versus the alternative of a national immunization program. The model applies a 5 year time horizon, with 1 monthly analytical cycles for children less than 1 year of age and annually thereafter. Three scenarios were compared to the base case reflecting the actual distribution over the different breastfeeding modes as present in Indonesia; i.e., the population under 2 years old with (i) 100% exclusive breastfeeding, (ii) 100% partial breastfeeding and ( iii) 100% no breastfeeding. Monte Carlo simulations were used to examine the economic acceptability and affordability of the rotavirus vaccination. Results: Rotavirus immunization would effectively reduce severe cases of rotavirus during the first 5 years of life of a child. Under the market vaccine price the total yearly vaccine cost would amount to US$ 65 million. The incremental cost per quality-adjusted-life-year (QALY) in the base case was US$ 174 from the societal perspective. Obviously, it was much lower than the 2011 Indonesian Gross Domestic Product (GDP) per capita of US$ 3495. Affordability results showed that at the Global Alliance for Vaccines and Immunization (GAVI)-subsidized vaccine price, rotavirus vaccination could be affordable for the Indonesian health system. Increased uptake of breastfeeding might slightly reduce cost-effectiveness results. Conclusion: Rotavirus immunization in Indonesia would be a highly cost-effective health intervention even under the market vaccine price. The results illustrate that rotavirus immunization would greatly reduce the burden of disease due to rotavirus infection. Even within increased uptake of breastfeeding, cost-effectiveness remains favorable. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.