Many web search engines retrieve enormous amounts of irrelevant information in answer to users’ queries. The semantic web provides a promising approach to improve search operation. For specific domains, ontologies can capture concepts to help machines deal with data semantically. Our aim in writing this paper was to show how to measure the closeness (relevancy) of retrieved web sites to user query-concepts and re-rank them accordingly. We therefore proposed a new relevancy measure to rerank retrieved documents. We termed the approach ‘‘ontology concepts’’ and it on the domain of electronic commerce. Results suggested that we could re-rank the retrieved documents (web sites) according to their relevancy to the search query. Our method depends on the frequency of the ‘‘ontology concepts’’ in the retrieved documents and uses this to compute their relevancy. 2010 Elsevier B.V. All rights reserved.