The cases of fourteen adolescents with fifteen physeal fractures of the tibial tuberosity were reviewed to more accurately define specific fracture patterns, to establish treatment for the different types, and to determine the incidence of complications. A modified classification scheme with a greater emphasis on intra-articular extension of the fracture and communution of the tuberosity was devised. Closed or open reduction, as necessary, gave satisfactory results. The primary indications for surgery were: (1) displacement of one or more fragments of the tuberosity anterosuperiorly, and (2) extension of the fracture through the proximal tibial ossification center into the knee joint, with disruption of the joint surface. There appears to be an increased incidence of pre-existing Osgood-Schlatter disease (ipsilateral and contralateral) in patients who have an acute tuberosity injury. Complications are rare. The theoretical possibility of the subsequent development of genu recurvatum appears unlikely, since most of these injuries occur when the physis of the tuberosity is undergoing normal closure.