Antidromic unit driving was utilized to demonstrate afferent projections from prefrontal cortical (PFC) and quasi-cortical structures (main olfactory bulb, MOB; anterior olfactory nucleus, AON; basolateral amygdaloid nucleus, BLA) to the ventrostriopallidal region (VSPR) of the rat. In all regions explored, a substantial number of antidromically invaded neurons were found following electrical stimulation of the VSPR. In addition, both the AON and the amygdalostriatal zone harbor cells with branched axons which innervate the MOB and the VSPR and the agranular insular cortex and the VSPR, respectively. These results support and extend previous neuroanatomical and neurophysiological data on afferent connections of the VSPR and emphasize the fact that several regions of the basal forebrain, which are actively involved in processing of olfactory information, and the VSPR, are more closely interrelated than hitherto suspected.