Posterior transfer of the tendon of the anterior tibial muscle through the interosseous membrane to the calcaneus to prevent or correct a calcaneus deformity was performed in twenty patients (thirty-nine feet) who had a myelomeningocele. The average age of the patients at the time of the operation was 4.6 years, and they were followed for an average of six years. Satisfactory clinical and radiographic results were obtained in thirty-seven (95 per cent) of the thirty-nine feet. Two patients, one who was unable to walk and one who walked at home only, had a mild equinus deformity of the left foot. No patient had a clinical calcaneus deformity, but there was radiographic evidence of talipes calcaneus in one patient (two feet). The anterior tibial muscle functioned more consistently when the operation was performed after the patient was four years old and in patients who had a fifth lumbar or first sacral motor level.