The test for antibiotic residues in milk carried out by the Milk Marketing Board (MMB) of England and Wales was increased in sensitivity from 0.02 iu/ml penicillin or equivalent to 0.01 iu/ml on January 1, 1986. The Veterinary Products Committee (VPC) has just completed a review of those intra-mammary antibiotic preparations which had licences of right. When assessing data for product licences the VPC decided that the concentration of antibiotic residues in milk should not exceed the concentrations listed in the 1969 Report of the Joint FAO/WHO Expert Committee on Food Additives. In this publication the level of 0.006 ppm for penicillin corresponds to 0.01 iu/ml which is the level that the MMB will also be using.