This study aims to study was to insulate and investigate the impact of some probiotic bacteria from different sources of milk and milk products in the reduction of cholesterol. Out of fourteen tested bacterial isolates, isolate no. (LAB 8) from raw cow's milk was the most potent isolate that reduced cholesterol by 33.07%. The cholesterol reduction potentiality by the isolate no (LAB 8) was optimized to 53.3% by studying and controlling the different cultural conditions as incubation temperatures, incubation periods, pH, cholesterol concentrations, carbon sources, nitrogen sources, phosphorus sources and UV radiation exposure. The highest ratio of cholesterol reduction by isolate no (LAB 8) was obtained after 6 days of incubation at 37ºC in basal medium of cholesterol well-adjusted to pH 7, with addition of cholesterol (0.75 g/L) as a substrate, maltose (1.0 g/100 mL) and after exposure to UV radiation for 60 min. The selected bacterial isolate no. (LAB 8) was identified biochemically by VITEK®2 as Lactobacillus plantarum.