Field potential and single unit recordings were used to assess the connections of the olfactory tubercle (OT) with the main olfactory bulb (MOB) and the piriform cortex (PC) in urethane-anesthetized rats. Current generators of depth profiles evoked in OT following MOB stimulation were localized 300 microns superficial to those elicited by PC shocks, suggesting that afferents from the MOB and PC end in different regions of the OT. Following MOB and PC stimulation antidromically invaded neurons were recorded in the ventral pallidal regions of the OT and in the vicinity of the islands of Calleja, respectively. These results demonstrate that the OT, which receives a monosynaptic input from the MOB, projects back to the bulb and that the PC seems to be also reciprocally linked with differentiated structures in the OT.