Clinical mastitis in dairy cows is a serious problem. An insufficient attention is still paid to their electronic recording and analysis in the Czech Republic. The article sumarizes the issues of mastitis diagnostics and especially the possibility of on-line recording using the web application „Recording of Diseases and Treatment“ (an Internet module for breeders ČMSCH, a. s.). This application brings a modern evidence of mastitis not only according to clinical symptoms but also according to the pathogenic agents. At the same time, the application records the used medicaments, so in the future will be possible to evaluate the consumption of medicaments for the mastitis treatment. The possibilities of evaluation of clinical mastitis at the farm and the basic analytical tools offered by the application are presented in the second part of the article.