Progression of slip is apt to cause complications including osteonecrosis and osteoarthritis. Such complications result in a poor prognosis for the joint. Therefore, to diagnose slipped capital femoral epiphysis (SCFE) while it is still mild is important to avoid complications as well as to prevent further slippage. In Japan, as the number of obese patients increases, obesity seems to be involved in the onset of slip both biomechanically and endocrinologically. We need to take care of obese children as they comprise a reservoir for SCFE patients. For severe slip cases, treatment is difficult owing to significant deformity of the femoral head with or without such complications as osteonecrosis and osteoarthritis. Transtrochanteric anterior rotational osteotomy is a promising option for preventing further slippage as well as to improve the congruity of the joint.