Abstract Background: Synaptosomal-associated protein 25 (SNAP-25) may be contribute to the pathogenesis of fibromyalgia Syndrome (FMS) by affecting the release of neurotransmitters. Objectives: We aimed to investigate the relationship between the SNAP-25 gen (DdeI = rs1051312 and MnlI = rs3746544) polymorphism and the temperament and character traits. Methods: A total of 85 female patients diagnosed with FMS and 70 age-matched healthy female subjects were enrolled into the study. The Temperament and Character Inventory (TCI) were performed on all the patients. SNAP-25 gene polymorphism was determined in the patients group and controls group. Results: No significant difference between groups was found regarding the distribution of SNAP-25 MnlI polymorphism (p > 0.05), but it was seen that the frequency of TC genotype for DdeI gene was higher in the patients group (p < 0.05). Increased hazard avoidance was found in the patients group (p < 0.05). When TCI scores were assessed in terms of SNAP-25 gene polymorphism, no statistically significant relationship was detected between the TT, TG, GG genotypes for MnlI gen and TCI scores (p > 0.05). However, increased hazard avoidance was detected in patients with TC genotype for DdeI gene compared to patients without such genotype. Discussion: SNAP-25 might be an etiological factor in FMS pathogenesis and might affect personality traits of FMS patients by mediating neurotransmitter release.