A total of 16 moulds was isolated and identified from 12 blue mouldy Tulum cheeses collected from retailers in Erzurum, Turkey; 12 were Penicillium roqueforti and 4 were Geotrichum candidum. The P. roqueforti isolates were grown in yeast sucrose broth at 5, 12 and 25 degrees C for 10 days, then extracted with chloroform and acetone and the extracts were examined for the presence of patulin, penicillic acid, roquefortine and PR toxin using thin layer chromatography. All of the P. roqueforti strains had toxin-producing ability at 5, 12 and 25 degrees C, eight produced only at 5 and 12 degrees C and six could not produce toxin at 5 degrees C.