Congenital Achilles tendon contracture is an autosomal dominant disease which is relatively rare. The disease manifests itself as 'toe walking'. Since the clinical condition is relatively benign, it is easy to be overlooked by the clinicians. To the patients, it presents problems of ambulation and activities of daily living. We present a case of 23 year old man who has been walking on his toes. The patient had a difficulty in squatting and tieing shoes and performed poorly gym activities. The patient's father and brother also walked on toes, which made the patient become indifferent to his condition. Upon physical examination, plantarflexion contractures of both ankle joints were 10 degree and the knee were 5 degree. We could not find any abnormal findings in motor or sensory function tests of both lower limbs. Deep tendon reflexes on patella and ankle were within normal range. There were no abnormalities in ankle X-ray, electromyography, blood sample test including muscle enzymes. Gait analysis showed increased ankle plantarflexion moment during entire gait cycle, increased knee flexion during terminal stance, and decreased both knee flexion during initial swing.