Introduction: Several studies have demonstrated the role of high cholesterol in different diseases. A diet high in cholesterol or saturated fats can impair the cognitive function. The aim of this study was to investigate the impact of simvastatin on spatial memory of rats receiving a high-fat diet. Materials and Methods: In this study, 35 adult male Wistar rats were divided into five groups (N=7). The subjects were trained for five days four times a day in Morris water maze to find a hidden platform. Time elapsed and distance travelled for finding the hidden platform were considered as criteria for learning. Probe trial was used for evaluation of memory retrieval. Results: Consumption of high fat diet for four weeks reduced learning ability in the high-fat group, which spent longer time and travelled a longer distance compared to the control group. However, oral administration of simvastatin at doses of 5 and 10 mg improved memory function. Memory function in rats treated with the drug had a significant difference with that of in the high-fat group. However, no significant difference was found between the groups treated with different doses of simvastatin. Conclusions: simvastatin improves spatial memory performance in adult male rats receiving high-fat diet.