The aims of the present study were to investigate the occurrence of aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂) in dairy cow feedstuff samples collected from four west provinces in Iran and estimate the corresponding concentrations of aflatoxin M₁ (AFM₁) in milk during winter and summer in 2014. A total of 160 feed samples consisting of corn silage (n = 40), alfalfa hay (n = 40), straw (n = 40) and barley (n = 40) were analyzed using high-performance liquid chromatography with a fluorescence detector method. AFB₁, AFB₂, AFG₁ and AFG₂ were detected in 82.5%, 69.37%, 43.12% and 41.87% of the feed samples, respectively. The concentration of AFB₁ in 65% (26/40) and 10% (4/40) of corn silage and straw samples was higher than the European Union limit, respectively. Estimation of the total corresponding concentration of AFM₁ in milk was evaluated as 20.16 and 35.68 ng/l during summer and winter, respectively.