99mTc-methylene diphosphonate (99mTc-MDP) scintigraphy of peripheral joints was studied by visual evaluation (Visual Assessment) of the scintigrams and by a computerized region-of-interest (ROI) method without, or with a reference region (ROI method or Corrected ROI method). Sixteen rheumatoid patients and a total of 477 peripheral joints were studied and the results compared with clinical joint activity evaluated by joint palpation. The ROI method without a reference proved to be insensitive and hence unsuitable for clinical use. The results of Visual Assessment and the Corrected ROI method correlated well with each other and with clinical joint activity. The sensitivity of the methods in detecting a clinically inflamed finger joint was: ROI 6%, Corrected ROI 71% and Visual Assessment 75%. The corresponding figures for peripheral joints of the feet were as follows: 28%, 41% and 58%. We conclude that, for clinical use, Visual Assessment of the scintigram is adequate and the method of choice.