The objective of this research is to evaluate the ability of clay minerals to adsorb aflatoxin B₁ (AFB₁) in vitro. Fourteen clay minerals from different sources in Thailand and commercial adsorbents including bentonites and toxin binders were tested for AFB₁ adsorption capacities. Our results indicated that the clay minerals were capable of sequestering AFB₁ from aqueous solution differently. The experimental data were fitted to modified Freundlich model better than Langmuir model to investigate adsorption capacities and affinity constant. The S-shaped isotherms were observed for these clay minerals and commercial adsorbents. The clay minerals had maximum capacity (Q_max) ranged from 7.10 × 10^-4 mol/kg to 4.76 × 10^-3 mol/kg whereas the commercial adsorbents had Q_max ranged from 8.21 × 10^-4 mol/kg to 4.52 × 10^-3 mol/kg. The distribution constant (K_d) for the clay mineral samples and commercial adsorbents were in the ranges of 2.15 × 10⁵-6.70 × 10⁷ and 2.52 × 10⁵-4.71 × 10⁵, respectively. This in vitro method may be useful for accurately predicting the efficacy of adsorbents before testing in vivo.