The objective of the studies was to evaluate the hygienic quality of raw milk from individual milk producers during a one year period. The total number of bacteria in one ml of milk was evaluated by the use of BACTO-SCAN 8000 equipment. It was found that the percentage of producers of the highest hygienic quality milk (up to 10⁵ bacterial cells/ml of milk) was significantly higher in winter (9.2%) and in spring (12.89%) than in summer (1.57%) and in autumn (1.44%). The highest number of producers of milk of the lowest quality (more than 10⁶ bacterial cells/ml of milk) was in summer and in autumn. It is suggested that the higher percentage of producers of milk of a good quality in winter and spring resulted from better conditions for milk cooling. Probably most milk producers cool milk in cold water or at room temperature. The observed differences in bacterial contamination of milk during a one year period indicate the necessity for using special equipment for milk cooling.