Background: The aim of this study was to determine the effect of probiotic fermented milk beverage on lowering cholesterol level and liver function biomarkers in male Wistar rats produced by our scientists for the first time. Materials and Methods: For this investigation, male Wistar rats (n=30), at the same age and weight were randomly divided into 5 groups. 2 control groups were fed a standard diet and fat enriched diet and 3 trial groups were fed with probiotic (1 ml), lovastatin (10 mg/kg) and probiotic with lovastatin for respectively 21 days. Probiotic fermented milk beverage was produced with 5 Lactobacillus casei strains (5×109) isolated from Iranian traditional fermented dairy products. At the end of experiments the cholesterol, HDL, LDL, AST, ALT, ALP, LDH and CPK were assayed. Results: Results showed that the serum levels of total cholesterol, LDL and HDL increased significantly in rats fed with selected fat diet. Oral administration of probiotic and lovastatin showed significant reduction of cholesterol level from 164.3 ± 13.63 to 101.3 ± 2.27 and 108.0 ± 3.342, respectively. There was no synergy between medication and probiotic. The LDL levels in 3 trial groups were significantly lower than the control group with a fat enriched diet. There was no significant difference in the levels of CPK, ALT and AST compare to fatty drinks, but ALP and LDH levels in beverage group significantly increased compare to the fat control group. Conclusion: Based on to the results, it seems that the fermented beverage has the ability to lower cholesterol and has no side effect on the hepatocyte system of rat's liver.