M1 aflatoxin is a potent hepatocarcinogen which may be present in milk, due lo the intake of B1 aflatoxin contaminated feedstuffs by dairy cattle. In France, monitoring programmes have been set up in 1976 for the detection of M1 aflatoxin in milk and dairy products. More appropriate and more sensitive methods (using immunological techniques, for example) are now available for the determination of M1 aflatoxin in dairy products. For 1978, 6 246 milk samples have been examined and divided into three classes : below 0,05 - 0,05 to 0,5 - more than 0,5 mug M1 aflatoxin/l milk. According to this classification, two major periods of contamination occurred in France, from 1978 to 1984 and in the winter seasons of 1988 to 1991. Some highly contaminated samples, occasionally containing up to 5 mug M1 aflatoxin/l milk, were found during the winter seasons of 1978-1983. Between 1984 and 1988, and from 1991, the number of contaminated samples was quite low. Presently in France, the dairy production is almost totally below the limits proposed by the European Community.