Objectives. To clarify the change of peripheral CD4+CD25+ regulatory T lymphocytes in normal pregnancy and pre-eclampsia and to explore its role in the pathogenesis of pre-eclampsia. Methods. Twenty-seven women with pre-eclampsia, 27 with normal third trimester pregnancy and 27 healthy non-pregnant women were recruited. Blood samples were taken and surface antigen CD4 and CD25 were labelled with fluorescence-conjugated antibodies. CD4+CD25+ regulatory T cells were analysed by flow cytometry, and the proportion in T cells and the amount of regulatory T lymphocytes were calculated. Results. The amount and the proportion of regulatory T cells were not significantly different among non-pregnant, normal pregnancy and pre-eclampsia groups (p>0.05 for both). There were no significant differences in the proportion and the amount of CD4+CD25+ regulatory T cells between mild and severe pre-eclampsia subgroups (p>0.05 for both). Conclusions. No significant change of peripheral regulatory T cells was observed in the current investigation, suggesting other mechanisms rather than CD4+CD25+ regulatory T cells were involved in the pathogenesis of pre-eclampsia.