In order to test the hypothesis that Wegener's granulomatosis (WG) is associated with an ongoing immune effector response, even in remission, we examined the distribution of peripheral naive and memory T-lymphocytes in this disease, and analyzed the function-related phenotypes of the memory T-cell population. Peripheral blood mononuclear cells (PBMCs) were freshly isolated from WG-patients in remission (R-WG, n=40), active WG-patients (A-WG, n=17), and age-matched healthy controls (HCs, n=21). Expression of CD4, CD8, CD45RO, CCR7, interleukin (IL)-18Rα, ST2L, and FoxP3 were determined by four-color flow cytometric analysis. CD45RO and CCR7 were used for distinction between naive and memory T cells, IL-18Rα, ST2L, and FoxP3 for the assessment of Type1, Type2, and regulatory T-cells, respectively. In R-WG, the CD4⁺CD45RO⁺CCR7⁻ effector memory T-cell subpopulation (T_EM) was relatively increased, whereas the CD4⁺CD45RO⁻CCR7⁺ naive T-cell population (T_Naive) was decreased as compared to HC. The distribution of naive and memory CD8⁺T cells did not differ between R-WG, A-WG, and HC, nor did CD4⁺CD45RO⁺CCR7⁺ central memory T cells (T_CM). In contrast to HC, the percentage of CD4⁺T_Naive cells in R-WG correlated negatively with age, whereas CD4⁺T_EM cells showed a positive correlation. In R-WG, a skewing towards Type2 T cells was observed in CD4⁺T_EM cells. No differences were detected in FoxP3⁺CD4⁺T_EM cells between R-WG and A-WG, whereas the FoxP3⁻CD4⁺T_EM cells were increased in R-WG and decreased in A-WG as compared to HC. Collectively, peripheral blood homeostasis of CD4⁺T cells is disturbed in R-WG with the persistent expansion of non-regulatory CD4⁺T_EM cells. These cells might be involved in relapse and may constitute a target for therapy.