Introduction: Aflatoxins are secondary toxic metabolites produced by certain group of Aspergillus species in suitable conditions. These toxins are highly toxic, immunosuppressive, mutagenic, teratogenic and carcinogenic metabolites. The purpose of this study was to detection aflatoxin M 1 concentration in mother′s milk from rural area of Khorrambid town of Fars Province. Materials and Methods: In this study, 87 milk samples of mothers were collected by cluster sampling methods in the period between June and July 2011 and the amount of aflatoxin M 1 was measured by a competitive ELISA method. Results: From 87 mother′s milk, 24 (27.6%) samples were contaminated with aflatoxin M 1 with mean concentration of 0.56 ΁ 1.23 pg/ml (range 0.13-4.91 pg/ml). Conclusion: The amount of aflatoxin M 1 in mothers′ milk was lower than 50 ng/l (Europe Union and Iranian standard). Detection of Aflatoxin M 1 in mothers′ milk is due to consuming contaminated food. This contamination not only threatens the health of the mothers but also has irreversible effects on the growth and health of their babies.