Objective To characterize the immune reaction in SD rats exposed to trichloroethylene (TCE) and to identify the gene expression profiles involved in skin after TCE exposure. Methods Fifteen percent of TCE was injected intradermally into the rat back (100 μL/120 g) at intervals of 7 days. Whole blood was collected 24 h after the fifth or seventh intradermic administration of TCE. The percentages of CD4+ and CD8+ of T lymphocytes were measured by a flow cytometer. The concentrations of IFN-gamma and IL-4 in the serum were semi-quantified by ELISA. Total RNAs of skin samples at 3 h or 24 h after the seventh dose of TCE in SD rats were extracted, and gene expression profiles of these tissues were analyszed by rat toxicology U34 array of Affymetrix. Results Obvious decline of CD4+ in T lymphocytes was observed in the TCE-administer group. No significant concentration differences in IFN-gamma and IL-4 were found between TCE-treated and control rats. Gadd45a and Mel were significantly up regulated in skin tissue 24 h after TCE exposure. The expression regulation of immune response factors was as active as proteins associated with lipid metabolism and synthesis process in these skin samples of SD rats exposed to TCE. Conclusion T-helper type 1 cells mediate immune response can not be elicited in TCE-treated SD rats, but certain immune disorder can be induced. Objective To characterize the immune reaction in SD rats exposed to trichlorethylene (TCE) and to identify the gene expression profiles involved in skin after TCE exposure. Methods Fifteen percent of TCE was injected intradermally into the rat back (100 μL / 120 g) at intervals of 7 days. Whole blood was collected 24 h after the fifth or seventh intradermic administration of TCE. The percentages of CD4 + and CD8 + of T lymphocytes were measured by a flow cytometer. The concentrations of IFN-gamma and IL-4 in the serum were Semi-quantified by ELISA. Total RNAs of skin samples at 3 h or 24 h after the seventh dose of TCE in SD rats were extracted, and gene expression profiles of these tissues were analyszed by rat toxicology U34 array of Affymetrix. Results Obvious decline of CD4 + in T lymphocytes was observed in the TCE-administer group. No significant concentration differences in IFN-gamma and IL-4 were found between TCE-treated and control rats. Gadd45a and Mel were significantly up-reg The expression regulation of immune response factors was as active as proteins associated with lipid metabolism and synthesis process in these skin samples of SD rats exposed to TCE. Conclusion T-helper type 1 cells mediate immune response can not be elicited in TCE-treated SD rats, but certain immune disorder can be induced.