Progressive ankle valgus is an insidious deformity that may develop during childhood due to a variety of etiologies including neuromuscular disease, skeletal dysplasia, chromosomal anomalies, and clubfoot. This may be concomitant with, or mistaken for, hindfoot valgus. The surgical options for treatment include supramalleolar osteotomy or hemiepiphysiodesis of the medial distal tibial physis. We report the rationale and technique of retarding medial malleolar growth by means of inserting a single 4.5-mm vertical screw. In a population of 31 children (50 feet), we have observed satisfactory improvement of ankle valgus with low morbidity and without permanent physeal closure. This represents a safe, predictable, and effective solution for children who present with progressive and symptomatic ankle valgus.