Antibiotic resistance in humans and animals is a significant and growing concern. The “UK Five Year Antimicrobial Resistance Strategy 2013-2018” mentions more targeted treatment following diagnostics as part of the strategy. Organic dairy farmers have always been at the forefront of reducing antibiotic usage, e.g. selective dry cow therapy has been in the standards from the very beginning. However, there has not been a major breakthrough in reducing antibiotic usage in the treatment of clinical mastitis. A recently launched bacteriological test kit has been validated under UK conditions and may be used on farm, potentially enabling farmers to select which cases of mild or moderate grade mastitis require antibiotic treatment (Gram positive cases) and which are likely to cure spontaneously (Gram negative cases). The effect of using this test and selective treatment on overall mastitis and milk quality parameters on farm has not been studied in the UK, and this is an area in need of research. In a large scale US study selective treatment of clinical mastitis compared with a conventional treatment protocol led to a 49 % reduction in cows receiving antibiotics, with no significant differences in clinical and milk quality parameters. Selective treatment of clinical mastitis is tried in an ongoing field lab involving 10 organic dairies. Apart from the benefits of reduced antibiotic usage, there is potential for a significant economic benefit to the farmer.