The Aspergillus awamoir-fermented black soybean, possessing enhanced functional properties, was previously suggested to be a potentially functional ingredient in the formation of healthy foods. In this study, the effect of heat treatments (40-100°C for 30 min) on the changes of total phenolics and anthocyanin contents, mutagenicity and the antimutagenicity of fermented black soybeans against 4-nitroquinoline-N-oxide, a direct mutagen, and benzo[a]pyrene, an indirect mutagen, on Salmonella Typhimurium TA100 and TA98 were examined. Results revealed that the heated-fermented black soybean showed no mutagenicity. Heating the fermented black soybean at 80 or 100°C for 30 min resulted in a reduced antimutagenicity with the methanol extract. Reduction in antimutagenicity varied with the test strains of S. Typhimurium and the type of mutagens examined. However, the fermented black soybean still possessed antimutagenicity after exposure to 100°C for 30 min. Contents of total phenolics and anthocyanins reduced significantly (p ＜ 0.05) as the heating temperature was raised to 40 and 80°C, respectively. Reduction in antimutagenicity of the fermented black soybeans after heating might be due to the lower anthocyanin content.