ObjectiveThis study aimed to assess the prevalence of the total aflatoxin in peanuts, and their concentration level.Material and MethodThis cross-sectional survey was conducted in seven district of Ulaanbaatar, the capital city of Mongolia,from March to December 2015.A total of 41 samples of peanuts were randomly collected from the survey area, from March to December2015. An ELISA test was used for detection the total aflatoxins(B1+B2). The relative humidity andtemperatures of the storage areas were measured at the time of sampling the peanut.ResultsThe Frequency statistics analysis showed that 61% of all analyzed peanut samples had detectablelevels of the total aflatoxinat 0.05 μg kg-1. The prevalence of samples contaminated with the totalaflatoxins(B1+B2) were higher among analysed samples of the tree nuts, peanuts imported from China,and canned nuts (P<=0.01). Levels of the total aflatoxins were less than the maximum permissible limitsof 15 μg kg by the regulation of European Union and worldwide. The mean values of the storage relativehumidityat the time of sampling peanuts were higher than the recommended storage relative humidity incorn cereals (<13%). Furthermore, the mean values of the storage temperatures at the time of samplingpeanuts were higher in groundnut peanuts, cedar’s nut and peanuts imported from China than therecommended level of the storage temperature in corn cereals (10°C-21°C).Conclusion:The prevalence of the total aflatoxin in peanuts was higher. The level of the total aflatoxins were less thanthe maximum permissible limits of 15 μg kg-1 by the regulation of European Union and worldwide. Thestorage relative humidity and temperatures of peanuts may encourage the growth of fungi-producingaflatoxins. Thus, a national strategy for the elimination of aflatoxin in foods is needed in Mongolia.