The authors analyse 7 cases which presented the criteria of ankylosing spondylarthritis and HLA 27 positivity, together with those of defined or classical rheumatoid polyarthritis with positive results in the latex test and the Waaler-Rose reaction in the joint fluid and/or the serum. The sex distribution, 6 men and 1 woman, was the same as for that disease. The clinical manifestations were very variable, with a predominance of localized, peripheral oligoarthritis in the lower limbs. Repeated iritis occurred in three cases. Two presented subcutaneous nodules on the elbow. All cases showed bilateral sacroiliitis; syndesmophytosis was rare. The overall clinical picture indicated rather a combined spondylarthritis than pure spondylarthritis. It is suggested that the occurrence of spondylarthritis in a subject with the HLA 27 gene might modify the response to the etiological factors of rheumatoid arthritis. These cases may thus be considered as a new type of combined or secondary spondylarthritis.