Twenty-six patients with ankylosing spondylitis and 10 control subjects had quantitative dorso-lumbar and sacroiliac scintigraphy performed using 99mtechnetium methylene diphosphonate. No difference was found in the mean uptakes of radionucleide at each vertebral level or in the sacroiliac joints between the diseases patients and controls. No correlation was found between radionucleide uptake and radiological score, pain and tenderness assessments. The large variation in quantiative measurements resulted in a large overlap between control and diseased patients and it is unlikely that scintigraphy will be of diagnostic value in the absence of improved methodology.