Post-milking teat disinfection, is there still something interesting to write about this topic? It has been widely covered since it has been proven to reduce the incidence of new intramammary infections. Although the state-of-the-art is well-known, we are often surprised by how this step is performed daily on the farm. This article will underline the importance of teat disinfection after milking. The worldwide regulatory positioning will give us some insights on how a teat dip is evaluated during the registration process. We’ll have a close look at the EU biocide directive, the main active substances, and other ingredients such as emollients and film forming agents that can be found in the teat dip/spray formulations in order to prevent mastitis. Finally, because post-milking teat disinfection is not effective if not properly applied on the teats, the principles of a correct application will be reviewed. The terms teat dip/teat dip solution/post-milking teat dip (PMTD) or teat disinfectant products will be used equally as general terms to describe solutions applied on the teats after milking.