The test chemical, Xylene, was evaluated for its genetic properties in a battery of tests consisting of a test for mitotic gene conversion in yeast, gene mutation tests in bacteria, gene mutation tests in culture mammalian cells and in vivo chromosome analysis in rat bone marrow cells. This series of tests provides a sensitive screen for the detection of substance which produce mutagenic and/or clastogenic alterations. A high percentage of known mammalian mutagens and carcinogens demonstrate activity in one or more of the tests conducted in this evaluation, and positive results in one or more of these tests are an indication that the test substance has mutagenic and/or carcinogenic potential and that further analysis to define the limits of expression of this potential is warranted. Negative results in all of these tests suggest that the test material lack genetic activity but are not sufficient for an unequivocal determination of genetic safety.