ELISA-based methods for the identification of the staphylococcal enterotoxins on occasion give positive signals that are false. The ones examined have been due to naturally occurring enzymes and non-toxin proteins. The most commonly recommended approaches for the elimination of false positive signals is the heating of food extracts (70°C, 30 min) or treating the samples with normal animal sera (0.1 vol serum to 1.0 vol. Food extract). While these approaches may be effective in the elimination of non-toxin positive signals, our data show that such treatments generally, reduce, inactivate or remove the toxins present in food extracts. Studies with enterotoxin in its native and heat altered/reactivated forms in mushrooms showed partial reduction (for small amounts of toxin) of toxin when exposed to heat (70°C) or treated with some lots of normal animal sera.