Abstract The effects of implementing food safety measures including pre-requisite programs (PRPs) and/or Hazard Analysis Critical Control Points (HACCP) on the microbiological quality of raw and pasteurized milk during four years was investigated in one of the biggest diary plant in Serbia. On the dairy farm, the measures included training of farmers, investments in the infrastructure of gathering points for the collection of raw milk and transportation, improvement of hygiene and decrease of the number of small farmers. As a result of these measures, the contribution of raw milk with of lower total plate count (TPC) in total raw milk quantity decreased over time. As a result of HACCP system implementation in the dairy plant, TPC of pasteurized milk decreased from 3.32 ± 0.48 till 3.11 ± 0.30 log CFU/ml. Eight months after HACCP system was implemented, a significant decrease in TPC from 3.11 ± 0.30 till 2.18 ± 0.54 log CFU/ml in pasteurized milk which could be related to the additional investments covering pasteurisation unit and automated cleaning and disinfection system. The research confirmed constrains of a solely HACCP system without adequate PRPs. Food safety improvements through PRPs and HACCP both on farm level and in the dairy plant present a basis for the production of dairy products.