Several authors have suggested the involvement of T lymphocytes and various cytokines in the pathogenesis of atopy, proposing that both membrane-bound and soluble forms of the low-affinity receptor for the Fc region of IgE (FceRII/CD23) may play a major role in IgE-related responses, The aim of this work was to compare the levels of the soluble form of CD23 (sCD23) between atopic and non-atopic subjects, Two indirect markers of T cell activation (soluble forms of CD25 and CD8) were also measured, Assays were performed by enzyme-linked immunosorbent assay of sera from 102 atopic and 67 non-atopic subjects. We observed no significant differences in the values of the sCD23, sCD8, and sCD25 between patients and controls. All markers were negatively correlated with age and positively correlated among themselves, The results suggest that the possible involvement of the molecules here studied in the pathogenesis of atopy is not translated into changes of their serum concentrations, which discards a possible diagnostic profit from their measurement.