Waterbike injuries.

Jet skiing is a rapidly growing sport. The craft incorporate safety features and the manufacturers issue detailed safety instructions. Racing is conducted with adequate attention to clothing, safety and insurance. However, casual use is widespread and is sometimes irresponsible. Serious injuries to riders are uncommon: dental and knee injuries are described. A case of renal contusion and a head injury were caused by other riders and two potentially fatal injuries illustrate the risk for other water users. The number of injuries associated with the use of personal watercraft is likely to increase and may be influenced by appropriate organization or regulation.