4 cases of chronic osteomyelitis in children and adolescents are described. The first one concerns a girl with severe plasmacellular osteomyelitis of the right upperarm. As the treatment with antibiotics failed a partial resection of the right humerus, followed by plastic covering of the resulting defect was successful. Two further cases of chronic metatarsal osteomyelitis of both feet could be classified as a kind of "sclerosing osteomyelitis Garré", mostly corresponding to the clinical feature of the "chronic recurrent multifocal osteomyelitis" (Björkstén et al., 1978). Furthermore, a case of chronic ostitis localized in the symphyseal area is described, the clinical symptoms of which were resembling to the cortical osteoid, a special kind of sclerosing osteomyelitis. It is suggested that these different forms of chronic osteomyelitis in children are caused by bacterial infections. Nevertheless, this hypothesis remains to be proved. The problems of the differential diagnosis are discussed. Generally, the only therapy with antibotics is not successful, whereas the combination of removing of the inflammatory process with plastic covering of the bone-defect usually results in recovery.