Mastitis in cattle is an infection of the mammary gland caused by infection, toxins and/or trauma. Currently, it is assumed that there is a correlation between higher amounts of residual milk and the incidence of clinical mastitis. The amount of residual milk can be exa - mined using different methods. Higher amounts of residual milk may result from an insufficient teat condition and individual detachment settings of milking units. To date, scientific literature has already discussed the relationship between high amounts of residual milk, undermilking and the occurrence of clinical mastitis. The present paper reviews the current status of knowledge regarding residual milk and risk of mastitis.