The effects of blockade of muscarinic acetylcholine receptors (mAChR) in rat cerebral cortex on learning and memory were studied by the use of passive and active avoidance tests. Injection of propylbenzilylcholine mustard (PrBCM) into frontal, parietal and occipital cortex decreased mAChR dose dependently, as assessed by 3H-quinuclidinylbenzilate binding studies. Bilateral injection of PrBCM into frontal and/or parietal but not occipital cortex impaired passive avoidance learning. The results suggest that intact muscarinic neurotransmission is important for registration and recall, but not retention phases of the learning and memory process. Alkylation of mAChR by PrBCM also caused impairment in the performance of active avoidance task.