An infant boy underwent hip disarticulation for infantile fibrosarcoma immediately after birth. His rehabilitation began when he was 4 mos old and involved training with his left (residual) leg. He could stand with support at 12 mos. His initial prosthesis fitting was performed at the age of 13 mos. He could stand and walk with support at 15 mos of age and could walk with no additional support and go up and down stairs at 2 yrs. A single-axis prosthetic knee joint was introduced at the age of 2 yrs 3 mos. His first gait using a hip prosthesis was successful, and his prosthesis was replaced at appropriate intervals with no major problems. The authors believe that the key to achieving a successful prosthetic gait in children is good communication among the medical team, which should comprise an orthopedic doctor, rehabilitation doctor, nurse, physical therapist, prosthetist/orthotist, and the patient's parents.