Aflatoxin M(1) (AFM(1)) and cyclopiazonic acid (CPA) were determined in 48 samples of grade A-C and ultra-high-temperature (UHT)-treated fluid commercial milk from São Paulo, Brazil, from July to December 2004. AFM(1) and CPA determinations were carried out by HPLC. Results showed 37 (77.1%) positive samples for AFM(1) at levels of 0.011-0.251 microg l(-1) milk, which were below the tolerance limit for AFM(1) in milk as adopted by Brazilian regulations. Mean levels of AFM(1) in grades A-C and UHT milk were 0.060+/-0.080, 0.056+/-0.063, 0.064+/-0.041 and 0.075+/-0.048microg l(-1), respectively. CPA was detected in two samples (4.2%) of grade A milk at levels of 6.4 and 9.7 microg l(-1). This is the first report of the occurrence of CPA in milk in Brazil. It was concluded that the incidence of AFM(1) in milk traded in São Paulo is low, but the simultaneous occurrence of CPA, even at low levels, warrants concern about AFM(1) in milk and milk products.