We are interested in the trophic influence of inhibitory synaptic transmission during neuronal maturation. The morphology of dendrites in the gerbil lateral superior olive (LSO) was examined following pharmacological blockade of glycine receptors during postnatal development. The normally occurring change in dendrite morphology during the third postnatal week was prevented. Dendrites had a significantly greater number of branch points, and their arbors were more spread out along the frequency axis in the region of LSO where glycine receptor density is greatest. An identical result has recently been obtained when the glycinergic projection to the LSO was functionally denervated during development. We conclude that glycinergic transmission modulates the maturation of dendrite form during development.