Previous observations indicate that the output linkages from motor cortex (area 4) to triceps brachii motoneurons develop relatively late in the postnatal kitten. Responses in multiple, simultaneously-recorded EMG's from facial, forelimb and proximal hindlimb musculature to intracortical microstimulation appear over gestational days 107-111 (about 41 days postnatally). Thus, output from the motor cortex to alpha motoneurons develops in a synchronous, rather than a sequential manner across the area 4 homunculi.