The antimutagenic activity of chlorophyllin, retinol, beta-carotene, vitamin-C, and vitamin-E against complex mutagenic environmental and dietary mixtures was examined. The mutagenicity of dichloromethane extracts of coal dust, diesel emission particles, airborne particles, and tobacco snuff and an aqueous extract of fried beef was tested in the presence or absence of chlorophyll, retinol, carotene, vitamin-C, or vitamin-E in the Ames/Salmonella assay utilizing strain (TA-98). Chlorophyllin at 6.9 micromoles (micromol) per plate micromol/plate inhibited 93 percent of the mutagenic activity of the coal dust extract. Approximately 29 percent of its activity was inhibited by 1.72micromol/plate retinol or 3.45micromol/plate carotene. Vitamin-E at 13.8micromol/plate inhibited less than 16 percent of its activity. Vitamin-C was ineffective against coal dust. Against the diesel particle extract, 3.45micromol/plate chlorophyllin inhibited 94 percent of its activity. Retinol at 1.72micromol/plate and carotene at 3.45micromol/plate inhibited 31 and 16 percent of the diesel particle mutagenicity. Vitamin-C and vitamin-E were ineffective. Chlorophyllin at 1.72micromol/plate inhibited 91 percent of the mutagenicity of the airborne particle and fried beef extracts. Approximately 40 percent of the mutagenicity of airborne particles was inhibited by 1.72micromol/plate retinol and 3.45micromol/plate carotene; vitamin-C enhanced the mutagenicity of the airborne particles. Retinol at 1.72micromol/plate inhibited 48 percent of the mutagenicity of the fried beef extract. Chlorophyllin at 6.9micromol/plate inhibited 68 percent of the mutagenicity of the tobacco snuff extract. Retinol, carotene, and vitamin-E at 138micromol/plate inhibited tobacco snuff mutagenicity to the extent of 29, 16, and 20 percent. The authors conclude that chlorophyllin is a more effective antimutagen than retinol, carotene, vitamin-C, or vitamin-E. Chlorophyllin may be potentially useful in preventing health hazards associated with genotoxic agents.