The aims of the present study were (1) to evaluate total mold count in feedstuffs (corn silage, corn, dried alfalfa, cottonseed meal, cottonseed, soybean meal, canola meal, barley, wheat bran, concentrate, sugar beet pulp and wheat straw), (2) to isolate and identify mold species based on macroscopic colony characteristics and microscopic morphology, (3) to quantify the level of aflatoxin B1 (AFB1) and (4) to determine the content of aflatoxin M1 (AFM1) in raw milk. Dairy farms were classified according to milk yield per day in low (<2000 Kg/day), intermediate (2000-5000 Kg/day), high (5000-10000 Kg/day) and very high milk production (>10000 Kg/day). Feedstuffs and raw milk samples were randomly collected from 16 dairy farms of Khorasan Razavi Province during cold (autumn and winter) and warm (spring and summer) seasons according to ISIRI 2581. Aflatoxin content of feedstuffs and milk samples was detected with ELISA technique. Results showed that the mold contamination of feedstuffs (except wheat straw) in cold seasons were significantly (P<0.05) higher than those of warm seasons. The most and least contaminated feedstuffs were dried alfalfa (4.51 log10cfu/g) and corn silage (1.29 log10cfu/g), respectively. The most predominant mold species isolated from feedstuffs in warm and cold seasons were Aspergillus (31.03% and 35.82%), Penicillium (22.02% and 20.34%), Mucor (11.41% and 13.18%), Cladosporium (9.01% and 12.03%) and Alternaria (9.28% and 5.73%), respectively. The measured contents of AFB1 in cottonseed meal, canola meal, wheat bran, sugar beet pulp and straw differed significantly (P<0.05) among all dairy farms. The contents of AFB1 in all feedstuffs during cold seasons were higher than those of warm seasons. The content of AFM1 in raw milk samples of dairy farms did not show significant differences with each others but the AFM1 contents in raw milk samples obtained from fall (84.76 ng/L) and winter (86.89 ng/L) were significantly (P<0.05) higher than those of spring (66.25 ng/L) and summer (63.78 ng/L). Although, the mean contents of AFM1 in raw milk samples were lower than the maximum recommended limits by ISIRI but 31.25 percent of samples in fall and winter were more than those of the maximum recommended limits by ISIRI.