Soon after its introduction, relevance feedback turned out to be of much value in Information Retrieval. The method yields a new query that should match the users information need with better results than the initial query does. In order to reformulate the initial query, a (Rocchio) learning algorithm is frequently used. Another approach, which is relatively new and origi- nates from artificial intelligence research, is the use of a genetic algorithm. In this paper, we explain both algorithms and we compare relevance feedback using a Rocchio algorithm with relevance feedback using a genetic algorithm. We report the effectiveness of the two approaches to relevance feedback in the context of information filtering.