About one third of motoneurons stimulated intracellularly evoked dorsal root potentials (DRP) in the lumbar segments of the isolated and perfused frog spinal cord. Axon collaterals were found in one of the 22 motoneurons filled with HRP (horseradish peroxidase) through the stimulating electrode. In further experiments injecting individual motoneurons with cobalt, and filling the ventral roots with HRP or cobalt, the frequency of occurrence of axon collaterals was about 2% of the number of labelled motor cells. It is suggested that the presence of motor axon collaterals is not indispensable in the generation of the DRP evoked by ventral root or motor cell stimulation.