Taking into account the number of teeth which are yearly irreversible traumatised during sport activities, the general use of mouthguards would contribute positively to the prevention of dental injuries. Custom-made mouthguards are more comfortable to wear and offer better retention and protection than stock and mouth-formed mouthguards. Different kinds of materials are available on the market for the construction of mouthguards. A polyethylene-polyvinylacetate copolymer (EVA) is the most suitable material. EVA allows the inclusion of hard or soft layers within the mouthguard. The thickness of a mouthguard is important for the reduction of applied forces to teeth: energy absorption capacity increases with material thickness. Increased thickness however, is associated with a reduction of comfort. Therefore, it is important that dentists take the patients' wishes and demands on both comfort and protection into consideration. A description of the clinical and technical method for the construction of a custom made mouthguard is given.