To investigate the role of the basolateral amygdala (BLA) in the reacquisition of heroin seeking, we studied the effect of BLA inactivation after heroin re-exposure in the presence of drug-conditioned cues. We employed a heroin conditioned place preference task [Leri F, Rizos Z, 2005. Reconditioning of drug-related cues: a potential contributor to relapse after drug re-exposure. Pharmacol Biochem Behav 2005;80:621-30.], where after initial conditioning and subsequent extinction, rats received a single reconditioning session (explicit compartment-heroin re-pairing), followed by a test of heroin seeking 24 h later. Rats were infused with GABA(A)/GABA(B) agonists (muscimol and baclofen, 0.03 and 0.3 nmol, respectively/0.3 microl) or vehicle, either 15 min or 6 h following the heroin reconditioning session. Animals that received vehicle infusions, whether they were given 15 min or 6 h following reconditioning, showed a significant preference for the heroin-paired compartment 24 h later. However, inactivation of the BLA 15 min post-reconditioning, but not 6 h following reconditioning, completely blocked the reacquisition of heroin seeking. These results suggest that the BLA plays an important role in a putative learning process initiated by drug re-exposure which may underlie the process of relapse.