Abstract: The effects of glucocorticoids on brain functions such as modulation of learning and memory are well documented. This study was conducted to examine the involvement of acetylcholine muscarinic receptors (mAChRs) of the baso-lateral amygdala (BLA) in the impairment effect of dexamethasone on memory retrieval. Adult male Wistar rats (220-250 g) were bilaterally cannulated in the BLA by stereotaxic surgery. The animal were trained and tested in the step-through apparatus, that consisted of two compartments which were connected via a small door, after one week. The rats were trained by induction of electric shock (1 mA, 3 sec) and then thay were tested for memory retrieval 24 h later (without receive shock). The time of latency (Step-through latencies) for entering the place of receiving the sock, the dark compartment of the instrument and the time spent by rats in this chamber (Time spent in dark chamber) were recorded for evaluation of the passive avoidance memory retrieval. Administration of the dexamethasone (2 mg kg-1, s.c.) before testing impaired memory retrieval. This effect of dexamethasone was reversed by pre-test administration of different doses of pilocarpine (1, 2 μg/rat, intra-BLA), a muscarinic receptor agonist. Whiles, Pre-test co-administration of low doses of scopolamine (0.3 and 0.5 μg/rat, intra-BLA), a muscarinic receptor antagonist, with the ineffective dose of the dexamethasone (0.5 mg kg-1, s.c.) impaired memory retrieval. However, the same doses of pilocarpine and scopolamine without dexamethasone did not affect memory processes. Our findings indicate that mechanisms of the mAChRs of the BLA may be mediates the impairment effect of dexamethasone on memory retrieval.