We studied the expression of various cell surface molecules (CD25, CD28, CD29, CD45RO, CD56, LFA-1, VLA-4) on peripheral blood CD4+ T-cells in 6 relapsing-remitting multiple sclerosis (RR-MS) patients. Furthermore, changes in the expression pattern of these surface markers during intervals of increased disease activity, which was measured by gadolinium (Gd-DTPA) magnetic resonance imaging (MRI) were examined. Although several patients showed signs of increased disease activity during the observation period, this was not paralleled by a relevant change in the expression of these activation and adhesion molecules.