Three group Ia muscle spindle afferent axons were labelled with horseradish peroxidase and terminations in lamina VI examined. Eleven perikarya were contacted by the three fibres; these were examined using a post-embedding immunostaining technique for GABA. Three neurons were found to be positively labelled for GABA. It is likely that these cells are involved in inhibition of primary afferent fibres and non-reciprocal inhibition of motoneurons.