Juvenile and adolescent "Chronic Recurrent Multifocal Osteomyelitis" (CRMO) is described on the basis of literature and analysis of 43 own cases (23 cases in children or adolescents). This systemic, non-purulent inflammatory disease occurs mainly metaphyseal in long bones, in pelvic bones or as spondylitis and is not as rare as it seemed. Basis of the disease is a primarily chronic, sterile, in phase of onset often monotopic (e.g. clavicle) and later frequently polytopic osteomyelitis, possibly triggered by an immuno-pathological process (e.g. Proprionibacterium acnes), and showing histologically plasmacellular invasion and a sclerosing process in different stages. Association with pustulous dermatosis (psoriasis, acne, palmo-plantar pustulosis) is found in about 25 % of children and adolescents and in more than 50 % of the adult patients. 5 differents types of distribution of osteomyelitic lesions can be found by using Te99m-bone scan primarily, of which the "pelvic type" is the most common. Because of the close neighbourhood of meta-/epiphyseal osteomyelitic focuses, "sympathetic arthritis" with synovitis is seen frequently. A therapeutic approach with azithromycine and calcitonine is presented.