The installation of automatic milking systems (AMS) is becoming more common around the world, as well as larger herd sizes. Risk factors for mastitis in farms using AMS may be different from farms using conventional milking systems (CMS). The reason behind this difference is the different management practices between CMS and AMS. On AMS farms mastitis detection is based on screening with sensors, whilst at CMS detection is done cow side during milking. Another dissimilarity is that udder preparation in AMS farm is done automatically, that is the process is always carried out with the same intensity.