One of the most common criticisms about the external validity of lab experiments in economics concerns the representativeness of participants usually considered in these studies. The ever-increasing number of experiments and the prevalent location of research centers in university campuses produced a peculiar category of subjects: Students with high level of laboratory experience built through repeated participations in experimental sessions. We investigate whether the experience accumulated in this way biases subjects’ behaviour in a set of simple games widely used to study social preferences (Dictator Game, Ultimatum Game, Trust Game, and Prisoner’s Dilemma Game). Our main finding shows that subjects with a high level of experience in lab experiments do not behave in a significantly different way from novices.