Rotavirus diarrhoea is associated with high childhood mortality in developing countries. A new vaccine was recently licensed in Mexico. The objective of this study was to assess the effectiveness of routine childhood vaccination by this new vaccine in a developing country. We constructed a decision tree to compare two alternatives: "no vaccination programme" and "vaccination programme". The estimates used for disease incidence, vaccine efficacy and coverage rates were derived from published data. We followed a hypothetical Nigerian cohort from birth to age five. The vaccine programme would prevent 284,000 cases of rotavirus diarrhoea annually and 6129 deaths due to the disease. In this study in a sub-Saharan country, we showed that rotavirus vaccination with a new vaccine substantially reduces the number of deaths from rotavirus diarrhoea and may be of great use in developing countries. (c) 2006 Elsevier Ltd. All rights reserved.