The aim of the current study is to evaluate IL-17 production and ROR gamma T, and IL-23R expression by iNKT, Th17 and gamma delta T cells in the peripheral blood of relapsing-remitting multiple sclerosis patients. Samples of peripheral blood from 21 relapse patients and 12 remission patients, and 15 healthy volunteers were stained with monoclonal antibodies for flow cytometry analysis. No significant differences in iNKT, gamma delta T and Th17 percentages were noted. The significant overexpression of ROR gamma T was observed in all three subpopulations - therefore, iNKT, gamma delta T and Th cells may be an important source of IL-17 shortly prior to the relapse.