We have retrospectively reviewed 53 cases (62 hips) with a diagnosis of slipped capital femoral epiphysis. After admission to our Hospital, a skin longitudinal traction was applied for 2 weeks. All patients were treated afterward with pinning in situ without manipulation in the operating room. Group A (31 hips) consisted of patients treated with smooth K wires and group B (31 hips) of patients treated with cannulated screws. We found a high incidence of pin penetration in group A (27 hips), whereas there was just one case in group B. Physeal closure was considered when 75% of proximal growth plate disappeared in the frog lateral view and both groups showed similar values (7 months). Chondrolysis was observed in just three cases in group A, and one case had an avascular necrosis. Few complications were observed compared with the high rate of pin penetration, and we suggest that preoperative traction may be a relevant factor contributing to the low incidence of avascular necrosis (1,6%).