Avulsion of the tibial tubercle is not common. Sixteen cases are recorded, with a mean age of 15 years 2 months. All subjects were boys, 15 cases were left-sided, and three individuals had other associated knee injuries. All were treated operatively. Immobilization time averaged 4.9 weeks, with a mean follow-up of 15 months. Fourteen subjects regained full motion and activity. Three complications were noted, none of which was associated with this injury. This injury occurs in a vulnerable period when the physis is undergoing physiologic changes that weaken its ability to resist tensile loading.