Treatment of Legg-Calve-Perthes disease remains, in spite of realized progresses, difficult and disturbing. The important factors for establishing diagnosis concerning definition, etiology, physiopathology and clinical manifestations are reminded. The role of present complementary investigations as well as their evolution are very important to better establish the prognosis and the treatment. The most important factors for treating and establishing the prognosis of LPC are: 1) age. The prognosis is good in almost every case before 5 years old, without any treatment; 2) the prognosis is not good after 9 years, also, very often, after surgical treatment; 3) area of the epiphyseal necrosis, particularly of the lateral pillar; 4) extrusion of the hip at any age. Today, there is always no causal treatment of Legg-Calve-Perthes disease. Conservative and surgical treatment aims to prevent deformities of the femoral head accompanied or not by articular incongruency, responsible for hip arthritis from the fourth decade. The place of conservative and surgical treatment as well as their complications are described; it aims to guide the spontaneous recovery with as little as possible, deformation of the femoral epiphysis.