Stress fracture of the femoral neck has been considered a typical injury of two age groups: active youths and elderly people with osteoporosis. Its occurrence in children with an open capital femoral epiphysis is rare, and only 11 cases have been reported. Here we report two cases, in a 12-year-old boy and a 5-year-old girl (among the youngest patients on record). This fracture can be classified as a compression fracture or a tension fracture. Although tension fractures are not uncommon in military recruits and young athletes, all 13 cases (including our two cases) of femoral neck stress fracture associated with an open capital epiphysis were compression fractures that were treated conservatively.