Objectives: The pathogenesis of widespread pain and increased tenderness in Fibromyalgia (FM) are still unknown. Recently, the role of central nervous system hyperexcitability is emphasized in pathogenesis of FM. The central sensitization was demonstrated with decrease in nociceptive flexion reflex (NFR) threshold in patients with FM. The NFR and cutaneous silent period (CuSP) are excitatory and inhibitory parts of the same spinal protective reflex, respectively. The aim of this study was to evaluate the changes in CuSP in FM.