To support programmers during program maintainance we present an approach which extracts concepts and relations from the source code. Our approach applies natural language parsing to sentences constructed from the terms that appear in program element identifiers. The result of parsing can be represented as a dependency tree. Then, we automatically extract an ontology by mapping linguistic entities (nodes and relations between nodes in the dependency tree) to concepts and relations among concepts. We applied our approach to a case study and assessed the result in terms of the support it can give to concept location, executed in the context of bug fixing.