Heated food systems contain hundreds of chemical compounds, some being mutagenic and others being antimutagenic. Studies have indicated that foods exposed to drying, frying, roasting, baking, and broiling conditions possess net mutagenic activity as assessed by the Ames/Salmonella/microsome mutagenicity test and the chromosome aberration assay with Chinese hamster ovary (CHO) cells. With the above-mentioned heat treatment of food, nonenzymic browning reactions are generally proceeding at rapid rates and are involved in the development of mutagens. Caramelization and Maillard reactions are two important pathways in the nonenzymic browning of food and are responsible for the formation of volatile aromatic compounds, intermediate nonvolatile compounds, and brown pigments called melanoidins. Heated sugar-amino acid mixtures possessed mutagenic activities which have been assessed by short-term bioassays. Purified Maillard and caramelization reaction products such as reductones, dicarbonyls, pyrazines, and furan derivatives have exhibited mutagenicity and clastogenicity. The water-insoluble fraction (WIF) of instant coffee and a model-system melanoidin (MSM) have been shown to inhibit the mutagenicity of known carcinogens--aflatoxin B1 (AFB1), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and benzo(a)pyrene (BP)--in aqueous dispersion. WIF and MSM were found to be effective binding agents for the carcinogens.