In this paper we describe a prototype system for information retrieval on the Internet. Our idea is that the Web has to be searched both semantically and syntactically. In order to automatically categorize the web pages on the fly we propose a novel approach based on ontology and semantic networks and we describe a prototype system based on the Intelligent Agent Paradigm. Preliminary experiments are shown and discussed while describing open problems and on-going research. Categories and Subject Descriptors H.3.3 [Information Storage and Retrieval]: Information Search Retrieval; H.4 [Information Systems Applications]: Miscellaneous General Terms Algorithms Keywords Information Retrieval, Semantic Network, Web Agents, Ontology