The pallidostriatal projection in the rat was investigated employing the PHA-L tracing technique. Following inotophoretic injections into the lateral aspect of the globus pallidus external segment, the ipsilateral striatum showed patches of dense anterograde labeling separated by areas containing sparse anterograde labeling and isolated retrogradely labeled neurons. The densely labeled patches did not correspond to any known compartments of the striatum. The retrogradely labeled neurons consistently showed similar distribution and morphological features reminiscent of striatal type II projection neurons. As all projection neurons of the striatum and all pallidal neurons are GABAergic, the complementary pattern of anterogradely and retrogradely labeled profiles from the globus pallidus suggest a possible mechanism whereby a horizontal inhibition may be exerted on groups of striatal neurons via the striato-pallido-striatal pathway.