Abstract The cleaning and sanitation of milking equipment could be consider a critical point in the milking procedure because a cleaning failure could influence the level of bacteria contamination of bulk tank milk. Aim of the study is to monitor the cleaning procedures of milking systems in 7 dairy cows farms in Lombardy and to find a relation between efficacy of cleaning system and the bacterial quality of bulk tank milk, remaining washing water through milking equipment and teat cup surface. Cleaning procedures were monitored with Lactocorder, that measured: duration, water temperature, turbulence, percentage of water in pipes, water conductivity of pre- and post-rinse and detergent phases. Results showed that the monitored farms the most of the cleaning parameters were lower than recommendations, in particular maximum water temperature (42.1±9.9°C) and percentage of water during detergent phase (76.1±13.9 %). A maximum temperature of detergent phase <40°C determined a high Standard Plate Count (SPC), thermoduric bacteria and Coliform Count (CC) of bulk tank milk, SPC and CC of teat cup surface. The research indicated that monitoring the efficiency of cleaning milking equipment with proper tools provide useful information about possible sources of contamination of bulk tank milk. Improving cleaning milking efficiency allow to improve milk quality.