Removal of aflatoxin B 1 from liquid cultures by resting and growing cells of Flavobacterium aurantiacum NRRL B-184 was studied. Spectrophotometic and thin-layer techniques served as aflatoxin assays. Cells grown in the presence of 5 ppm or higher levels of aflatoxin developed aberrant morphological forms. These toxin concentrations partially inhibited growth, and the nature of the inhibition suggested that aflatoxin interfered with cell wall synthesis. Incubation of 1.0 × 10 11 resting cells per milliliter with 7.0 μg/ml of aflatoxin B 1 during a 4-hr period facilitated complete toxin removal from a buffered aqueous medium. Autoclaved cells and cell wall preparations could remove a fraction of the aflatoxin of a test system. However, the toxin removed by autoclaved cells and cell walls could be extracted by washing with water but the aflatoxin B 1 removed by intact cells could not be extracted into the liquid phase. The uptake of aflatoxin B 1 by resting cells was sensitive to temperature and p H. Ruptured preparations of F. aurantiacum were not able to remove or modify the aflatoxin in an aqueous solution.