There has been a significant increase in the number of individuals participating in contact sports. As a result, every effort must be made to provide the athletes with protection against mouth injuries. In this review the use, construction and benefits of mouthguards in all sports has been described. There is unanimous opinion attesting to the benefits of such protective devices and in those sports where the athlete is required to wear a mouth guard, a dramatic decrease in the number and severity of injuries has been reported. Custom-fitted mouth guards should be used in many sports that do not already have a compulsory rule requiring their use. Physicians, dentists, trainers and coaches need to be educated on the data supporting the benefits described. Studies on performance enhancement as a result of mandibular orthopaedic repositioning appliances have also been reviewed. Long term studies are required to assess the claims of ergogenic enhancement utilising proper study design. Current evidence exists relating to the effects of psychological phenomena on athletic performance, and it is believed the placebo effect contributes to the findings of performance improvement.