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Introduction & Objective: A number of β-carboline alkaloids such as harmane are naturally present in the human food chain. Furthermore, some plants which contain β-carboline have behavioral effects such as hallucination. In the present study, the effect of intra-dorsal hippocampus injection of nicotinic receptor agonist on memory impairment induced by harmane was examined in mice. Materials & Methods: This study was conducted at Shahid Beheshti University in 2009. Two hundred and forty mice were anesthetized with intra-peritoneal injection of ketamine hydrochloride, plus xylazine which afterwards were placed in a stereotaxic apparatus. Two cannuale were placed in the CA1 regions of the dorsal hippocampus. All animals were allowed to recover for a total week before beginning of the behavioral testing. After that, the animals were trained in a step-down type inhibitory avoidance task and tested 24 hours after training to measure step-down latency as a scale of memory. Results: Pre-training and post-training, intra-peritoneal injection of harmane impairs inhibitory avoidance memory, but pre-testing injection of harmane did not alter memory retrieval. Pre-testing administration of high dose of nicotine (0.5 µg/mice, intra-CA1) decreased memory retrieval. On the other hand, pre-test intra-CA1 injection of ineffective doses of nicotine (0.1 and 2.5 µg/mice) fully reversed harmane induced impairment of memory. Conclusion: The present results indicated that complex interaction exists between nicotinic receptor of dorsal hippocampus and the impairment of inhibitory avoidance memory induced by harmane.