This document proposes a new method to re-rank web documents retrieved by search engines based on their relevance to a user's query using ontology concepts. It involves building an ontology of concepts for a given domain (electronic commerce), extracting concepts from retrieved documents, and re-ranking documents based on the frequency of ontology concepts within them. An evaluation showed the approach reduced average ranking error compared to search engines alone. The method was tested on the first 30 documents retrieved for the query "e-commerce" from search engines.