The purpose of this study was to determine whether long-term changes in synaptic efficacy can be induced in the pyramidal tract (PT). Tetanic stimulation of the PT induced long-term facilitation of PT input to spinal cord neurons. In contrast, tetanic stimulation of the pyramidal tract did not alter the efficacy of synaptic inputs of PT cells' intracortical axon collaterals to other cortical neurons. These findings suggest that the PT participates in motor learning by modulating the excitability of spinal cord neurons. The results also indicate that induction of LTP in the PT is dependent on postsynaptic mechanisms.