A comminuted coronal split fracture of the proximal tibial epiphysis is an uncommon injury in children. The authors evaluated and treated two patients who sustained an epiphyseal fracture through a partially closed proximal tibial epiphysis. Plain radiography and computed tomography with three-dimensional reconstruction showed a comminuted coronal split fracture of the proximal tibial epiphysis. Each patient underwent definitive operative fixation of the fracture and was followed at least 1 year after clinical union. A mechanism consisting of three-point bending on the tibial plateau is proposed.