Valgus deformity of the ankle in children is associated with a wide variety of clinical conditions. A retrospective review was performed of 17 children (29 involved extremities) with ankle valgus deformity who had been managed by use of a percutaneously placed, transphyseal medial malleolar screw. Median age at the time of surgery was 11 years, 2 months. Median postoperative follow-up was 2 years, 2 months. Tibiotalar axis and ankle mechanical axis were the best radiographic indicators of ankle valgus deformity. Fibular station and epiphyseal wedging were poor predictors of ankle alignment. Significant improvement in the tibiotalar axis (median, 12 degrees) was noted at follow-up, and the median rate of correction was 0.59 degree/month. Resumption of physeal growth and recurrence of deformity (rate of 0.60 degree/month) was seen when the screws were removed before skeletal maturity. The transphyseal medial malleolar screw is a minimally invasive, minimally morbid, technically simple method of reversible partial epiphysiodesis at the ankle and is an effective technique for the correction of ankle valgus deformity associated with a wide variety of clinical conditions in children.