Fibromyalgia (FM) is characterized by chronic widespread pain and tenderness. This study investigated the association of tenderness and spontaneous pain in FM using pressure stimuli and fMRI measures of brain activity before and after milnacipran treatment. Ninety-two female FM patients received milnacipran 200 mg/day or placebo in a 13-week, double-blind, placebo-controlled trial. Participants received individually calibrated painful or nonpainful stimuli randomly applied to the thumbnail. Tenderness (pain VAS) and brain activity (fMRI) were assessed at baseline and posttreatment. At baseline, all patients demonstrated pressure-evoked brain activity in regions associated with pain, including the insular and cingulate cortices, cerebellum, thalamus, and primary and secondary somatosensory cortices. After 12 weeks, experimental tenderness was reduced with milnacipran (Pฯญ.055 vs placebo). fMRI analysis revealed increased brain activity in the caudate nucleus, anterior insula, anterior cingulum, and amygdala with milnacipran. Placebo-treated patients showed activity in the parietal region and mid-insula. Signficantly greater pain-evoked activity was observed in the posterior cingulate/precuneus region in milnacipran-treated patients compared with placebo (Pฯฝ.05). The effect of milnacipran on experimental tenderness suggests an association between the clinical symptoms of FM and increased tenderness in FM.