A survey of the extent of bovine type human tuberculosis in Northern Ireland has been made from unselected material during the past 5 years.Only one case of bovine type pulmonary tuberculosis was found out of more than 1000 cases.The proportion of bovine type cases in the non-respiratory group was 4·3%; 3·3% of meningitis cases were of bovine origin.A marked decline in the extent of bovine type infection is shown to have occurred during the past 10 years. This is believed to be due to a great increase in the pasteurization of milk during this period. Milk was a particularly valuable food during the war, and pasteurization facilitated its distribution.