The aim of the present study was to investigate the possible connection between interleukin-6, the acute phase (relapse) of multiple sclerosis (MS), and depression. The authors determined and statistically evaluated the levels of interleukin-6 and its soluble receptor in the serum of 28 MS patients in relapsing, 14 MS patients in remission, and 20 control subjects, as well as the presence of depression among these individuals. The results of our study indicate that depression is not only very common during relapses of MS, but also that the levels of IL-6 increase during the acute phase of the disease, especially when depression is detected.