Hip problems in children are relatively rare but usually serious, potentially causing lifelong disability. Early diagnosis and treatment is, therefore, mandatory. The aim of this review is to discuss the most frequent diseases of the hip from birth to adolescence. The different affections are relatively closely related to age periods. After birth and in infancy, developmental dislocation of the hip (DDH) and septic arthritis are more prominent. DDH is not always present at birth and should regularly be checked for in the first 6 months of life. Septic arthritis is an emergency and should be adequately treated within 4 days of the beginning of the infection with open drainage of the hip. Transient synovitis and Legg-Calvé-Perthes disease (LCPD) are mostly found between 4 and 10 years of age. Transient synovitis is the most frequent hip disorder in that age group. It is a self-limiting noninfectious effusion in the joint without serious consequences. Differential diagnosis with septic arthritis should, however, be made. LCPD is an idiopathic avascular necrosis of the hip causing flattening and deformity of the femoral head, depending on the extent of the necrosis. Treatment by containment is aimed at favoring the remodeling of the deformed femoral head. Finally, between the age of 10 and 15 years, slipped capital femoral epiphysis (SCFE) should be the preferential diagnosis, especially in the limping obese boy. SCFE is an inferior and posterior displacement of the proximal epiphysis of the femur in the growth plate. It should be treated as an emergency with a screw fixation.