The therapeutical effect of levamisole in ankylosing spondylitis as well as the effect of this therapy on the immunologic parameters were to be examined. Since the sample consisted of 10 patients only, statistically relevant results were not to be expected. Only male patients with positive HLA-B 27 have been examined. The therapeutical effect after treatment of 3 months has been observed as good to very good. The immunologic parameters reacted in a mode which had formerly been described as immunomodulating.