The aim of this study was to see whether long-term potentiation (LTP) and/or long-term depression (LTD) of synaptic efficacy could be induced in the ventral horn of the rat spinal cord. Transverse slices were cut from neonatal rat spinal cords and maintained in vitro. Field potentials were recorded in the ventral horn in response to stimulation of the dorsal horn-intermediate nucleus region of the slice. Tetanic stimulation at 100 Hz (6 bursts of 50 pulses with 10 s between bursts) resulted in long-term potentiation in 25% of slices, long-term depression in 33% of slices and no long-lasting change of field potential amplitude in the rest. The long-term changes lasted at least 2.5 hours. The principal conclusion of the work is that LTP and LTD can be elicited in the ventral horn.