Maillard Reaction Product (MRP) prepared by heating (2 h at 121°C) a solution of 0.2 M glucose and 0.2 M histidine was added at different concentrations (0.23, 0.47 and 0.70%) to cold milk (either autoclaved reconstituted 10% nonfat milk solids inoculated with Pseudomonas fragi or raw milk) and stored at 5°C to evaluate its effect on growth of psychrotrophic microorganisms during refrigerated storage. Growth of micro-organisms decreased as the percentage MRP increased. P. fragi in autoclaved nonfat milk was inhibited more than was the natural flora in raw milk. An apparent bactericidal effect was observed at higher MRP concentration in autoclaved milk; however, this was not evident for raw milk.