Trichloroethylene (TCE) is a widely used industrial solvent employed mainly for degreasing and cold-cleaning metal parts. It is also used for dry cleaning, and in the production of a number of chemical products. It has been shown to induce liver and lung tumors in rodents, and have a variety of positive and negative results using in vitro and in vivo mutagenicity tests. In order to assist in the interpretation of the mechanism of carcinogenicity, TCE was tested for the ability to induce gene mutations and small deletions using the lacZ transgenic mouse model (MutaMouse). Male and female animals were exposed by inhalation to 0, 203, 1153, and 3141 ppm TCE, 6 h per day for 12 days. 14 and 60 days following the last exposure, animals were sacrificed and the mutation frequency in bone marrow, kidney, spleen, liver, lung, and testicular germ cells determined. The results of this study indicate that TCE did not induce base-change or small-deletion mutations as detected in this assay in any of the tissues examined. Environ. Mol. Mutagen. 34: 190-194, 1999. Published 1999 Wiley-Liss, Inc.