After reviewing types of sclerosis of the vertebral bodies and spondylodiscitides occurring near the vertebral discs, the causes of which are relatively well known, two observations of cases of chronic progressive sclerosing spondylodiscitis are described in detail together with their case history. The primary manifestation (in the lumbar vertebral column) is seen, apart from a discitis, in a relatively early and eventually homogeneous sclerosing of the spongiosa. The course of the disease is extremely protracted; after 1-5 years, other parts of the vertebral column are affected in a similar manner. Inflammatory parameters are definitely involved, and the nosological neighbourhood to angylosing spondylitis is discussed. In the absence of any other hints, it appears justified to assume non-specific chronic progressive sclerosing spondylodiscitis which begins monostotically and can proceed according to a polystotic pattern.