Sesame oil is one of the vegetable oiles that has different effects on body function. Some evidence indicates that unsaturated fatty acids can modulate learning and memory. So, in this study the effect of intramuscular and intrahippocampal injection of sesame oil on spatial learning and memory in N-MRI adult male rats is investigated. The animals were divided into 6 groups (n=7). At first stage there were 3 groups: control (no injection), normal saline sham and sesame oil test groups which received 0.1 ml normal saline and sesame oil injection intramuscularly 45 minutes before training every day. At the second stage animals were bilaterally cannulated in to the CA1 region of hippocampus and after recovery they were divided into the following 3 groups (n=7): control (no injection), normal saline sham and sesame oil groups which received 0.5ml sesame oil, respectively, in to the CA1 region of hippocampus immediately before training. Then each rat was trained in 30 trials every day for a total of 5 days using Y-maze and after one month the memory of all groups was tested (one session memory test). Data shows that sesame oil increased spatial learning. In memory test, there were no significant differences between the mean of correct responses of 5thday and one month later among groups and so the indication is that their memory has not been changed. In conclusion, it seems that sesame oil increases spatial learning task through their unsaturated fatty acids by changing the membrance fluidity and by lecithin as a precursor of acetylcholine.