Aflatoxins produced by Aspergillus flavus and A. parasiticus can be biotransformed into AFM₁, a carcinogenic metabolite excreted via urine and milk. Thus, study objectives were to determine the effects of dietary adsorbent, silicoglycidol clay (ATX), on urine AFM₁ concentration, total AF fluid excretion (urine + milk), and inflammatory biomarkers in dairy cows. Twelve primiparous lactating Holstein cows (279 ± 88 DIM and 675 ± 19 kg BW) were used in a replicated 3 × 3 Latin square design with 21-d periods: (1) Control (CON) consisting of basal TMR; (2) aflatoxin diet (AF) consisting of 100 µg of AFB₁/kg DM intake with basal TMR; and (3) an AF challenge similar to AF but supplemented with 0.10% clay in the diet (AF+ATX), top dressed on the basal TMR. For each period, urine and blood samples were collected on d 21. Statistical analysis was performed using the MIXED procedures of SAS (SAS Institute Inc., Cary, NC) with square, period within square, and treatment as fixed effects and cow within square as a random effect. Immunoglobulin G (158.0 ± 7.1 mg/L; P = 0.75) and haptoglobin (1.1 ± 0.4 µg/mL; P = 0.57) were similar across treatments. Concentration of AFM₁ in urine was 9.9 ± 1.2 µg/L for the AF diet whereas the inclusion of ATX resulted in 41% less AFM₁ in urine (P ≤ 0.04). Urine output was similar across treatments but, due to differences in effective AFM₁ exposure, urinary excretion was 2.33 fold greater in the AF challenged cows compared with those consuming ATX. Comparing AF to AF+ATX, excretion of AFM₁ via milk and urine was 28% and 57% lower, respectively. Total fluid transfer of AFM₁ was decreased from 26 ± 5.6% in the AF group to 11.7 ± 6.0% for the AF+ATX group. Cows that consumed AF had numerically 25.2% lower concentration of circulating haptoglobin compared with the AF+ATX diet, possibly indicating immunosuppression whereas the clay supplement seemed to have a restorative effect. These results suggest that AF may be immunosuppressive in the liver and it is primarily excreted via urine. Silicoglycidol clay effectively reduced AF transfer and excretion via urine and milk.