Automatic milking systems, or robotic milking systems, are now well established as a milk harvesting technology in Europe, Nth America and Australasia. This system is quarter based harvesting where human activity is not routinely required for milking or initial mastitis detection activities. Mastitis risk factors common with conventional milking are: environmental contamination, teat congestion and teat hyperkeratosis risk. The risk factors which differ include: pre-milking preparation, impact formation, and overmilking risk. Mastitis detection technology varies between automatic milking unit types, but all should be characterised by test sensitivity, false alert rate and the gold standard used for test assessment.