PURPOSE: To evaluate the activated zone of the supplementary motor area through motor and sensorystimula-tion of both hands by fMRI. MATERIALS AND METHODS: Twenty-four healthy volunteers, ranging in age from 20to 30 years, served as sub-jects. They were divided into four groups and performed one of the four activationtasks : complex movement, fine movement, touch sensation, heat sensation. Complex movement consisted of a fingertask in which sub-jects flexed and extended all fingers repeatedly in union, without the fingers touching eachother(group I). Fine movement involved a thumb task in which subjects flexed and extended the thumb repeatedlywithout touch-ing the other fingers(group II). Touch sensation consisted of a palm task in which another personrepeatedly drew a circle on the subject 's palm (group III), and heat sensation involved of a palm task in whichsubject 's palm was touched by another person with a 40 degreeC water-bag (group IV). F-MRI was conducted on acommer-cial 1.5-T scanner equipped with echo-planar imaging. After overlapping images were obtained using aZ-s-core, and the mean/curve in the MR devices was evaluated, the activated zone of the supplementary motor RESULTS: Thirty-two of 48 images(20 of the 24 men) revealed activated zones in the supplementary motor area. Ingroup I, activation was observed in five subjects, in three of whom it was bilateral (contralateral activation).In group II, activation was observed in five subjects, in one of whom it was bilateral. In group III, activationoccurred in five subjects(bilateral in four, and contralateral in three), and In group IV, activation was alsoob-served in five ; in three of these it was bilateral. CONCLUSION: Using fMRI, and in association with motor andsensory tasks, the supplementary motor area was activated in 66.7% of healthy volunteers (32/48).