Ottergem is a sub-municipality of Erpe-Mere in Flanders. It is located on the Molenbeek in the Denderstreek, southeast of East Flanders and belongs to the Arrondissement of Aalst. The sub-municipality is bordered by the sub-municipalities of Erondegem, Erpe, Mere, Bambrugge (and its hamlet Egem) and Vlekkem and the municipality Sint-Lievens-Houtem (sub-municipality Vlierzele). Ottergem has 500 inhabitants as of 1 January 2003 and an area of 1.55 km.