Information Retrieval systems are limited by the linguistic variation of language. The use of Natural Language Processing techniques to manage this problem has been studied for a long time, but mainly focusing on English. In this paper we deal with European languages, taking Spanish as a case in point. Two different sources of syntactic information, queries and documents, are studied in order to increase the performance of Information Retrieval systems. Categories and Subject Descriptors H.3.1 [Information Storage and Retrieval]: Content Analysis and Indexing—Indexing methods, Linguistic processing; H.3.3 [Information Storage and Retrieval]: Information Search and Retrieval—Query formulation General Terms Algorithms Keywords Information retrieval, natural language processing, shallow parsing