Mutagenicity tests were performed for components of the defoliant Agent-Orange with the Salmonella arabinose resistant assay system. These components included 2,4-dichlorophenoxyacetic-acid (94757) (2,4-D) and 2,4,5-trichlorophenoxyacetic-acid (93765) (2,4,5-T) along with butyl, isobutyl and isooctyl esters and the contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) (TCDD). Arabinose sensitive S-typhimurium-strain-SV50 was used as the tester strain. Rat and hamster liver S9 homogenate and S9 mix were used for metabolic activation. No mutagenic response to the test compounds was observed under any of the assay conditions used. With the use of activation, neither hamster nor rat S9 induced any mutagenic response. It seems likely that the compounds tested do not cause point mutations. Even without doubling no dose responses were noted in any of the study compounds. In all compounds, except for TCDD, variable toxicity was evident at the higher dose levels of 3333 and 10000 micrograms/plate.