OBJECTIVE: To determine whether there is any difference in regional cerebral blood flow (rCBF) and serum cytokine levels and association between clinical parameters and rCBF and serum cytokine levels in young females with fibromyalgia (FM). The other aim was to search whether the depression state has any effect on these two parameters. METHODS: Nineteen women with FM and 20 healthy women had 99mTc-HMPAO brain single-photon-emission computed tomography (SPECT) to evaluate rCBF. Serum interleukin (IL) levels (IL 1 beta, IL 2r, IL 6 and IL 8) were measured. Clinical and psychological evaluation was also carried out in FM patients and healthy controls. RESULTS: The patients with FM had significantly higher radioactivity uptake ratio in right and left caudate nucleus (p = 0.009, p = 0.001, respectively) than healthy controls. There was statistically significant decrease in the 99mTc-HMPAO uptake in the right superior parietal (p = 0.041), gyrus rectalis (p = 0.036) and pons (p = 0.023). FM patients had significantly higher serum IL 2r and IL 8 levels (p = 0.023, p = 0.011, respectively) than controls. Additionally, FM patients had significantly higher Fibromyalgia Impact Questionnaire (FIQ), Health Assessment Questionnaire (HAQ), and Hamilton Depression Rate scale (HDRS) scores (p = 0.000) than controls. Interestingly, the patients with mild depressive symptoms or without (i.e. HDRS-score < or = 16) had significantly higher serum IL 8 levels (p = 0.027) and increased radioactivity uptake ratio in the pons (P = 0.036) than the patients with more severe depressive symptoms (i.e. HDRS-score > 16). With regard to regional cerebral blood flow, significant correlations were detected between RSP and morning stiffness (r = 0.70, p < 0.01) and sleep disturbance (r = -0.53, p < 0.05), and between gyrus rectalis and FIQ score. There were significant correlations between LCN and IL-2 (P = 0.025), between RSP and morning stiffness (P = 0.006), sleep disturbance (P = 0.021) according to multiple regression analysis test. CONCLUSION: This study shows a significant increase in rCBF of caudate nuclei, a reduction in the pons, some cortical regions activity and a increase in IL 8, IL2r levels of young female patients with FM. These findings are more prominent in patients with low HDRS scores.