Aflatoxin M1 is a major carcinogenic compound that may be existed in dairy products. The aim of this study was to determine the occurrence of AFM1 in traditional yoghurt samples in Guilan Province (Northern Iran). Ninety samples of traditional yoghurts were collected during summer and autumn 2014. Enzyme linked Immunosorbentassay (ELISA) which is a rapid and sensitive method was used to determine the presence and levels of AFM1. 100% of the yoghurt samples were contaminated with 5 and 83 ng/kg of AFM1. In general, AFM1 in 20 samples (22.22%) were higher than the maximum tolerance limit (50 ng/kg) accepted by the European Union. It was therefore concluded that, high occurrence of AFM1 in yoghurt is a serious risk for public health.