Two-color flow-cytometric analysis on peripheral blood lymphocytes of 46 untreated multiple sclerosis patients (MS), 36 other medical disease patients (OMD) and 19 healthy control subjects (HC) was performed to know the relationships between T and B cell subpopulations. In MS patients we observed an increase of total lymphocyte count and an increase of CD4+CD29+ cells, which are adjuvant to B cell in antibody production. We hypothesized this change is related to the reduction of CD21+ cells, expressing B2 antigen which disappears after B cell activation. The unperfect balance of immune system in MS was also demonstrated by the increased level of CD25+ cells in relapsing-remitting patients and by the decreased level of CD4+ CD45RA+ (suppressor inducer) cells in progressive patients.