The efficacy of inactivation of aflatoxin B1 (AFB1, 2.0-2.6 mg per kg) in aqueous medium in exposure to 21 chemicals or their mixtures for two hours and for two days was evaluated by measuring the extracts on a fluorescence spectrophotometer. Reduction to less than 10% of the original AFB1 content within two hours was recorded when the medium contained 1.5% potassium permanganate, 2.5 and 5% Chloramin B (Lachema) or soda, and when there was 5% ammonia heated to 60 degrees C, 5% sodium hydroxide, potassium hydroxide or calcium hydroxide, or 50% chromosulphuric acid. AFB1 and other fluorescing metabolites were completely destroyed after two days of exposure to a 5% ammonia solution heated to 60 degrees C for the first two hours and after two days of exposure to 5% Chloramin B, 5% soda, 5% calcium hydroxide, 50% chromosulphuric acid, and mixture of 2.5% sulphuric acid with 0.75% potassium permanganage. Acids used alone had the lowest effectiveness.