In this study we investigated cytokine levels in patients with familial Mediterranean fever (FMF). Twenty patients and 20 healthy controls were included. Ten patients had acute attacks of FMF, whereas the other 10 were in the silent period. Patients with the acute exacerbation of FMF had higher soluble interleukin-2 receptor (sIL-2r), interleukin-6 (IL-6), tumour necrosis factor-alpha, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and fibrinogen levels than those in the silent period (P < 0.001) and controls (P < 0.001). In patients with acute attacks of FMF, interleukin-10 (IL-10) levels were not significantly different from those in the other patients or the controls (P > 0.05). In FMF patients IL-6, TNF-alpha, sIL-2r, ESR, CRP and fibrinogen levels increased with the acute-phase reaction, especially in the attack period. On the other hand, anti-inflammatory cytokine IL-10 levels did not increase as much as did the inflammatory cytokines. The balance between the cytokines may help us to understand the pathophysiology of FMF and to develop therapies. We conclude that the levels of the acute-phase reactants and the cytokines could be useful for diagnosis of acute exacerbations, follow-up and treatment. However, the cost of cytokine measurement analyses seems disadvantageous at present.