Ensemble learning is a well established machine learning approach that utilises a number of classifiers to aggregate the decision about determining the class label. In its basic form this aggregation is achieved via majority voting. A generic approach, termed EV-Ensemble, for evolving a new ensemble from an existing one is proposed in this paper. This approach is applied to the high performance ensemble technique Random Forests. This study uses a genetic algorithm approach to further enhance the accuracy of Random Forests, based on the EV-Ensemble approach. The new technique is termed as Genetic Algorithm based Random Forests (GARF). Our extensive experimental study has proved that Random Forests performance could be boosted when evolved using the genetic algorithm approach.