Psychrotrophs in milk and milk products are not surprising because these organisms are widely distributed in nature and common contaminants of dairy products. Storage of milk and such products for long period at refrigerated temperature has resulted in quality problems by the action of lipase and protease enzymes produced during their growth which is heat stable causing spoilage. The objective of study is to investigate the incidence of psychrotrophs in raw milk and spot light on their economic and public health importance as well as to study the effect of activation of lactoperoxidase system on the shelf-life of raw milk kept at room temperature(22 ± 1 ^oC) and refrigerator temperature (4 + 1 ^oC). Material, One hundred random samples of raw milk were collected in clean, dry and sterile sampling bottles (500 ml each) from dairy farms and shops (50 each) at different sites of the local markets in Alexandria Governorate. Result,All samples were contaminated with psychrotrophs with mean count of 1.50 x 10⁶ ± 3.3 x 10⁵ and 3.20 x 10⁶ ± 4.5 x 10⁵ cfu/ml in examined farm and market milk samples, respectively.The shelf life of raw milk with activation of lactoperoxidase system with Sodium thiocyanate (NaSCN) and Hydrogen peroxide (H₂O₂) at concentrations of (10:25, 14:30, and 30:100 ppm) has prolonged to 16, 16, and 24 hours when kept at room temperature and to 20, 20, and 30 hours when kept at refrigerator temperature, respectively.Conclusion, Strict hygienic measures should be highly recommended during production of raw milk, processing; transportation and storage of pasteurized milk to ensure a high quality product and to safeguard consumers from public health hazards.