The mouthguard is a resilient device or appliance which is placed inside the mouth to protect against injuries to the teeth, lacerations to the mouth and fractures and dislocations of the jaw. There is clear support in the scientific literature for the use of mouthguards in contact sports such as rugby. Moreover, there is evidence that mouthguards are effective in protecting against concussion and injuries to the cervical spine. There is a high level of acceptance of mouthguards by players and an increasing number are regularly wearing mouthguards. This is especially true among the elite players, but acceptance and wearing rates are moderately high among club players as well. There is strong support among players and researchers for mouthguard wearing to be made compulsory. It is generally recommended that: (i) mouthguards be worn during both practice sessions and games; (ii) the habit of wearing a mouthguard begins at an early age; (iii) mouthguards be regularly replaced while children are still growing; and (iv) adult players replace their mouthguards at least every 2 years. The selection of a mouthguard will depend on a number of factors including the age of the individual, effectiveness and cost. The type I (stock), or 'off-the-shelf', mouthguards are considered inferior when compared with the other available types, and their use is discouraged. Type II (mouth-formed) mouthguards come in 2 forms, the shell-liner version and the popular thermoplastic 'boil and bite' version. While the effectiveness of the shell-liner mouthguard was examined in one experimental study, no such research has been reported for the thermoplastic mouthguard. Type III (custom-fabricated) mouthguards are recommended for players playing in the more vulnerable positions and in the higher grades. Most experimental studies in which the effectiveness of mouthguards has been demonstrated have involved type III mouthguards.