Abstract: Objective The changes of lymphocyte subsets and liver dysfunction in patients with dermatitis medicamentosa-like of trichloroethylene were compared before and after treatments,to provide the clues for exploring the pathogenesis. Methods The lymphocyte subsets and liver dysfunction of 14 patients diagnosed as medicamentosa-like of trichloroethylene,including 9 cases of exfoliative dermatitis and 5 cases of erythema multiforme,were measured before hospitalization and 2-3 months after treatment (when the clinical use of glucocorticoid was stopped). Results The liver dysfunction was found at the beginning and the patients recovered after treatment. The percentages of CD3⁺, CD8⁺T lymphocyte cells were higher than the reference values (t=2.283 -6.841,P < 0.01),while the percentages of CD4⁺ (CD3⁺CD4⁺) T lymphocyte cell,NK (CD3^-CD16+56⁺) lymphocyte cell,B (CD3^-CD19⁺) lymphocyte cell and CD4⁺/CD8⁺ ratio were lower than the reference values both before and after treatments (t=-14.49——2.310,P < 0.01). The percentages of CD8⁺T lymphocyte and B lymphocyte cells of patients with exfoliative dermatitis were lower after treatment (t=2.814,2.877,P < 0.05).When lymphocyte subsets were compared among patients with erythema multiforme between before and after treatments,no statistically significant difference was noted. The numerical values of immunoglobulin M (IgM),immunoglobulin A (IgA) were lower after treatment (t=2.256,2.293,P < 0.05), while the numerical value of immunoglobulin G (IgG) had no statistically significant difference between before and after treatments (t=1.783,P>0.05). It was found that the GGT level at the beginning positive linear correlated with percentages of mature CD3⁺,CD8⁺ T lymphocyte cells (r=0.496,0.470, P < 0.05),while negative linear correlations were found between cholinesterase,albumin and mature CD3⁺,CD8⁺T lymphocytes cell (r=-0.567,-0.475,-0.501,-0.516,P < 0.05). Negative linear correlation was found between cholinesterase and lymphocytes cell after treatment (r=-0.608,P < 0.05). Conclusion Immune dysfunction may exist among the patients with dermatitis medicamentosa-like of trichloroethylene in a long time. DMLT may result from the joint action of cellular immunity and humoral immunity. The proliferation of CD8⁺T lymphocyte cells may involve the damaged mechanism of liver and skin.