In 1987, our group proposed the acronym SAPHO (Synovitis Acne Pustulosis Hyperostosis Osteitis) to identify a clinical entity with characteristic manifestations formerly described under a wide variety of names. Since our first description, several new points have been recognized. For example it has been demonstrated that the skin lesions are not necessarily concomitant with osteoarticular manifestations sometimes separated by a long time interval. There are also several arguments suggesting a relationship with spondyloarthropathy. In addition, pseudo-tumoral fibrosis of anterior thoracic lesions which may lead to venous compression have been observed. It is difficult to determine the frequency of SAPHO. Most of the cases reported were observed in western Europe or Japan. Now that the concept has been accepted by our British colleagues, the number of cases reported has increased steadily, perhaps suggesting a reason for the apparently low frequency in the United States. The pathogenesis is still unknown. There is some evidence however that Propionibacterium acnes infection may be involved, at least in some cases, but formal proof is still lacking. Treating patients with SAPHO thus remains a question of debate. Non-steroid antiinflammatory agents are currently the treatment of choice although certain authors have tried colchicine and sulfasalazine or methotrexate with little success. There remains a good deal of work to be done before we thoroughly understand the SAPHO syndrome but we can nevertheless assure our patients that this strange bone disease is neither a tumour nor an infection and is never severely invalidating.