Adsorbent use in aflatoxin (AF) contaminated diets is critical in alleviating detrimental effects of AF on dairy cattle performance. The objective of this study was to determine the effects of a commercially available aluminosilicate clay in a traditional lactation diet during an AF challenge on the presence of AF in milk, urine, and feces, and performance parameters of multiparous lactating Holstein cows. Sixteen multiparous, lactating, Holstein cows [BW (mean ± SD) = 758 ± 76 kg; DIM = 157 ± 43 d] were assigned to 1 of 4 treatments in a replicated 4 × 4 Latin Square design: no adsorbent and no AF challenge (CON), no adsorbent and AF challenge (POS), 113 g of aluminosilicate clay top-dressed on TMR (adsorbent; PMI Nutritional Additives, Arden Hills, MN) with AF challenge (F4), and 227 g of adsorbent with AF challenge (F8). For each period, milk was sampled 3 times daily from d 14 to 21, while feces and urine were sampled on d 14, 18, and 21. Statistical analysis was preformed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Fat-corrected milk (POS = 37.2, F4 = 39.2, F8 = 38.9 kg/d) and ECM (POS = 37.3, F4 = 39.3, F8 = 38.9 kg/d) increased (P = 0.05 and 0.04, respectively) as concentration of adsorbent in the diet increased. Lactose yield (kg/d) increased as concentration of adsorbent in the diet increased (POS = 1.67, F4 = 1.89, F8 = 1.74 kg/d; P = 0.05). A quadratic treatment effect was present for protein yield (POS = 1.20, F4 = 1.28, F8 = 1.24 kg/d; P = 0.01). There was a decrease in milk AFM1 concentration (POS = 0.33, F4 = 0.32, F8 = 0.27 µg/kg; P = 0.001) as concentration of adsorbent in the diet increased. A quadratic treatment effect was present for AFM1 transference (POS = 0.45, F4 = 0.49, F8 = 0.39%; P = 0.03). There was a decrease for AFM1 concentration in urine (POS = 2.10, F4 = 1.89, F8 = 1.78 µg/kg; P = 0.04) and feces (POS = 4.68, F4 = 3.44, F8 = 3.17 µg/kg; P = 0.05) as concentration of adsorbent in the diet increased. In conclusion, the adsorbent used in this study had a positive effect on milk production, milk components, and AF excretion in milk, urine, and feces.