INTRODUCTION AND BACKGROUND The test chemical@ R-04@ 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 substances 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 and indication that the test substance has mutagenic and/or carcinogenic potential and that further analysis Negative results in all of these tests suggest that the test material lacks genetic activity but are not sufficient for an unequivocal determination of genetic safety. The assumptions of mutagenic and carcinogenic potential or lack of potential are based on correlations between extensive data bases.