In recent years, there was a debate about the effects of gum chewing on various aspects of cognitive functioning. In this review, the results of previous studies are presented and summarized. There is a clear indication that gum chewing can improve various aspects of cognitive functioning including memory, attention and both executive and intellectual functioning. However, there is also clear evidence that chewing gum during cognitive tasks can adversely affect task performance. Therefore, it can be concluded that the replication of (beneficial or detrimental) effects of gum chewing on cognition has been proven to be very difficult. Consequently, the robustness of reported effects of gum chewing on cognition has to be questioned. Suggestions for future research are given.