A survey was undertaken to update and extend available information on the vitamin content of pasteurized milk as produced at processing dairies in mainland UK and to investigate regional, seasonal and breed effects. The concentration of total retinol in milk from non-Channel Island (NCI) breeds averaged 619/tg/lOOg in summer and 41-2/£g/100g in winter. Concentrations of /^-carotene were 31*5 and 105/tg/100 g in summer and winter respectively. Concentrations of retinol in milk from Channel Island (CI) breeds were similar, but concentrations of /^-carotene were on average 3 times higher. The concentration of vitamin D 3 in milk from NCI breeds was 0-033/ig/100 g in summer and 0026 /ig/100 g in winter. There was no marked seasonal variation in the mean concentration of total vitamin C (14-5 /*g/ml). Values for the concentration of B vitamins (/jg/ml) were: folic acid 0-060, vitamin B 12 0'0042, riboflavin 1-78, nicotinic acid 0-71, pantothenic acid 3-60, biotin 0-020, thiamin 0-46 and vitamin B 6 061. Seasonal variation in the concentration was most marked for folic acid (c.v. 17-4%) and to a lesser extent for vitamin B 12 (c.v. 10-3%). The only breed differences in the B vitamin content were for riboflavin and folic acid, the mean values obtained for milk from CI breeds being respectively 20 and 10 % higher than those from NCI breeds.Because of its high nutritive value and the quantities consumed, milk is one of the most important primary commodities in the British diet. In addition to protein, fat, carbohydrate and Ca, milk is also a significant source of many vitamins and trace elements.Although monthly averages of butterfat and solids-not-fat in raw milk are published by the Milk Marketing Board, no recent comprehensive data on the nutrient content of pasteurized bulk milk from the British herd are available. In the most recent edition of Composition of Foods (Paul & Southgate, 1978) all values, apart from riboflavin, vitamin C and most minerals (analysed in bottled milk by the * Present address: Academia Medyczna, Zaklad Bromatologii,