Bovine Somatotropin (BST) is a synthetic growth hormone that can increase milk yield in dairy cows by between 10 and 20 per cent. BST was approved for commercial use in the United States last year, where reaction from consumers, farmers and retailers to the use of the drug has been cool. For several years pharmaceutical companies have been testing and seeking official authorization to market BST in the European Union (EU). However, its introduction has been resisted by many farmers and most consumers because of concern for the health and welfare of the cows, the health of consumers and the possible effects on the economic viability of the small dairy farm. The use of BST does increase the milk yield but it also seems to be associated with a higher level of mastitis. It has also been suggested that the use of the hormone may also result in an increased incidence of anaemia, digestive disorders, enlarged hocks and lesions of the knees.