Cooling the milk is the best solution for extending the keeping quality of raw milk during storage and/or transportation. This is, however, not feasible in such cases as lack of cooling facilities, high ambient temperatures and distant transportation (Bjorck et al., 1979). Utilization of the lactoperoxidase (LP) system could be a practical alternative for the preservation of raw milk under these circumstances. Prolonged storage of raw milk at the refrigeration temperature poses additional problems due to proteolysis caused by proteinases of psychrotrophic bacteria (Nakai et al., 1964, Kehagias, 1982) which could bring about changes in physico-chemical properties of milk during cold storage. An altered distribution pattern of nitrogen has been reported by Youssef et al., (1975) and El-Deeb and Hassan, (1989) for raw goat's and ewe's milk stored at low temperatures. No detailed information is available in relation to proteolytic changes in small ruminants' milk preserved by the LP-system, although Kumar and Mathur, (1994) and Ghosh et al., (1994) observed negligible changes in various nitrogen fractions in raw cow and buffalo milk preserved with this system. The present study was, therefore, carried out to reveal the changes in various nitrogen fractions that may take place at refrigeration storage and under the influence of the LP-system in both ewe's and goat's milk samples stored at 20 degrees C or 30 degrees C for 16h. The changes in titratable acidity, rennet clotting time and thiocyanate content of milk samples were also followed during storage.