The objective of this article is to evaluate the presence of sex differences in expression of cytokines in both CD4+ and CD8+ T cells derived from peripheral blood of untreated multiple sclerosis (MS) patients. The predominance of females in MS and other autoimmune diseases may be related to their differential responses in many immunological settings. Recent data show beneficial effect of sex hormones on proinflammatory cytokine levels and on magnetic resonance imaging in MS. Better understanding of gender differences is warranted. In this study 124 MS subjects (M:F; 56:68) and 34 healthy controls (M:F; 12:22) were included. Stimulated peripheral blood-derived CD4+ and CD8+ T cells were analysed for interferon-gamma, interleukin (IL)-2, tumour necrosis factor alpha, IL-4, IL- 10 and IL- 13 production. There were no significant differences for these cytokines between male and female MS subjects in the whole group. Compared to males, female patients had higher proinflammatory cytokine levels in the progressive phase of the disease. In conclusion, the data presented indicate that cytokine production and sex differences in cytokine production might differ between disease phases, probably related to underlying disease mechanisms.