Abstract. The paper argues that a promising way to improve the success rate of preference-based anaphora resolution algorithms is the use of machine learning. The paper outlines MARS - a program for automatic resolution of pronominal anaphors and describes an experiment which we have conducted to optimise the success rate of MARS with the help of a genetic algorithm. After the optimisation we noted an improvement up to 8% for some les. The results obtained after optimisation are discussed.