Abstract: cases with active ankylosing spondylitis （AS） were treated with sulfasalazine（SSZ） for 3 to 23 montlis. 3 months, 6 months and 1 year after taking medicine,7 active index-es were observed, including the number of painful and swelling joints, morning stiffness,Schobertest,chest expansive degree, ESR and CRP. The results showed the indexes were remarkably improved except chest expansive degree. In patients who took SSZ more than 1 year,the rateof clinical remission was marked higher compared with that for only 3 or 6 months. Side-effectsof ssz usually occured in the first 3 months of therapy, but no one case discontinued the thera-peutic course owing to the side-effects, The study indicated that SSZ had a sure efficacy intreating active AS. Sufficient duration and proper dosage were of important signifficance to incr-ease the therapeutic efficacy. Persisting in taking SSZ （2.0/d） over 1 year, the higher tate ofclinical remission and good security would be expected.