Mastitis in dairy cattle is responsible for greater economic loss to the dairyman than any other disease. These losses are represented by loss in quantity of milk produced, lower quality of product and loss through sacrifice of animals sold to market because of severe mastitis. Until the last few years too little attention had been given to this important disease. The fact that there was no effective treatment for the condition was no doubt chiefly responsible. The discovery and development of new drugs during the last few years has found some of these agents to be effective against certain agents causing bovine mastitis. As a result considerable study and research is being conducted on this important problem.