This research was prompted by conflicting data in earlier studies on the nature of the deficit and the extent of recovery possible following deafferentation of a monkey's forelimb. Our approach to the problem utilized an avoidance conditioning technique, prolonged restraint of the intact forelimb in a straight-jacket as well as extension of the area of deafferentation to include, in different animals, the neck, the contralateral forelimb and an entire side of the body. In the free situation, in conformity with the observations of earlier investigators, animals with unilateral forelimb deafferentations did not use the affected extremity in an effective purposive manner. In the conditioning situation, however, monkeys were able to learn, as well as perform an already learned, conditioned response with the deafferented limb. In addition, they used the limb to reach for and grasp food when the intact limb was restrained. The presence or absence of neck afferents did not affect the results. When the deafferentation was extended to include the contralateral forelimb the animals used the originally deafferented limb purposively without restraint and in addition were able to use the limbs in a coordinated manner for ambulation as long as vision was intact. It is thought that the disparate results of previous workers were due to differences in testing technique. The present results appear to indicate that intact segmental reflexes are not necessary for purposive movements nor for ambulation. © 1963.