Early detection of intramammary infection (IMI) using clinical and laboratory methods focused on culture based evidence of pathogen is crucial for propose of diagnosis and effective treatment protocol to complete recovery. Current knowledge of a course of IMI in individual pathogens allows for a more accurate prognosis of antimicrobial treatment. The aim of the study was to evaluate the effectiveness of intramammary treatment of chosed IMI caused by Streptococcus uberis by category D penicillins using the MicroMastTM (CZ) on farm culture system in relation to antimicrobials consumption on the farm.