In the present study, 24 samples of Minas Frescal cheese and 24 samples of Minas Padrão cheese produced in the North-east region of the state of São Paulo, Brazil, were analysed for aflatoxin M1 (AFM1) by high-performance liquid chromatography (HPLC) between March and August 2008. AFM1 was detected in 13 (27.1%) samples at concentrations ranging from 0.037 to 0.313 ng g(-1). The mean concentrations of AFM1 in positive samples of Minas Frescal and Minas Padrão cheese were 0.142 ± 0.118 and 0.118 ± 0.054 ng g(-1), respectively. It is concluded that the incidence of AFM1 in Minas cheese may contribute to an increase in the overall ingestion of aflatoxins in the diet, hence indicating the need for the adoption of a tolerance limit for AFM1 in cheese in Brazil.