One hundred and fifty‐two samples of pasteurized milk, powdered milk, cheese and yoghurt, marketed in Campinas, Brazil in 1989–1990, were analysed for aflatoxin M1by the AOAC TLC method (visual quantitation) 980.21. Fifty‐two pasteurized milk samples were also analysed in 1992 by the AOAC HPLC method 986.16. Aflatoxin M1was not detected in the 1989–1990 samples. Four milk samples of the 1992 batch were contaminated at 73–370 ng/1. Except for the sample with 370 ng/1, which would have been also found positive by the TLC method, the detection of aflatoxin M1in 1992 reflects the higher sensitivity of the HPLC method, not a greater occurrence of the toxin. Contamination of milk and milk products with aflatoxin M1does not appear to be a serious public health problem in the city of Campinas at the moment.