Tennis is a popular racquet sport played by boys, girls, men and women. Tennis players frequently begin playing in childhood and may continue playing into late adulthood. Preadolescent and adolescent players have open growth plates and a reduced muscle power, lower level of coordination and smaller stature compared with adult players. The physical characteristics of the young tennis player mean that unique demands are placed on the developing athlete which can, in turn, be associated with different types and patterns of injury. The most common types of injury in tennis players of all ages are muscle sprains and ligament sprains secondary to overuse. These are a particular problem in the adolescent age group because, in general, this group begin playing with a lower level of physical conditioning. Fortunately, injuries in younger players are usually not longstanding and the overuse (chronic) problems seen in older players, such as patellar tendinosis and tennis elbow, are less common in younger players. Anatomically, lower extremity injuries are twice as common as those to the upper extremity or spine, with ankle injury being the most common. Prevention of injury in young tennis players, or at least a reduction in the incidence, is possible. Some traumatic injuries, including contusions, abrasions, lacerations and fractures, may be unavoidable as a result of aggressive play, but others may be prevented by monitoring equipment and the court surface to ensure a safe field of play. The prime target of prevention in young tennis players should be overuse injuries. The principles of 'overload' and staged involvement are of particular importance in this age group. A gradual, progressive increase in the intensity of tennis practice, the slow introduction of new court surfaces and a staged progression in the teaching of tennis skills can help to reduce the incidence of injury in young tennis players.