Aflatoxin M1 (AFM1) was determined by ELISA in 57 cheese and 10 milk samples collected from supermarkets and street milkmen during August in Bursa Province, Turkey. The highest AFM1 concentration was 810.00 ng/kg in full fatty white cheese. The incidence of AFM1 in the cheese was higher (89.47%) than that of milk (10%). The AFM1 in 7/57 (12.28%) cheese samples exceeded the Turkish AFM1 tolerance limits of 250 ng/kg, but none of the milk samples exceeded the FAO/WHO, European Union and Turkish tolerance limit of 50 ng/L.