Although psychological treatments are effective in treating fibromyalgia syndrome (FMS) patients, little attention has been given to the impact of these treatments on physiological parameters. The present study was the evaluation of the effects of operant behavioral (OB) and cognitive-behavioral therapy (CBT) for FMS on the cardiovascular, autonomic, and muscular systems. Pain intensity, baseline levels, and stress reactivity measures were assessed in 100 patients with FMS randomly assigning to OB (N=40), CBT (N=40), and an attention placebo (social discussion, AP, N=20) treatment groups. In addition, 30 age- and sex-matched Healthy controls (HC) were included for comparison. Surface electromyography (EMG) recorded from the trapezius muscle, blood pressure (BP), heart rate (HR), and skin conductance levels (SCL) were continuously recorded during adaptation and baseline, social conflict, mental arithmetic, and relaxation tasks. Additionally, pain and activity score by Multidimensional Pain Inventory (MPI) were recorded. Assessments were performed pre, post, 6 and 12 months following treatment. The OB and CBT groups reported significant and stable reductions in pain intensity (F(4;102) = 3.51, p<0.01). FMS showed significant lower EMG and elevated HR and SCL compared to the HC prior to treatment (Fs(4,130) > 5.51, ps<0.01) as an expression of lowered physical performance capability. Only, the OB group showed significant changes in EMG and HR at 6 month and 12 month after the treatment. Additionally the activity score was increased 12 month after the operant treatment (t (99) = −2.1, p<0.03). The enhanced muscle tension and decreased HR as well as the increased activity after the operant pain treatment suggest an enhancement of physical performance capability in FMS. Supported by grants of Deutsche Forschungsgemeinschaft to KT (Th 988-1/2), HF (FL 156/26, Clinical Research Unit 107) the Max-Planck-Award for International Cooperation, and from the National Institute of Arthritis and Musculoskeletal and Skin Diseases to DCT (AR44724) Although psychological treatments are effective in treating fibromyalgia syndrome (FMS) patients, little attention has been given to the impact of these treatments on physiological parameters. The present study was the evaluation of the effects of operant behavioral (OB) and cognitive-behavioral therapy (CBT) for FMS on the cardiovascular, autonomic, and muscular systems. Pain intensity, baseline levels, and stress reactivity measures were assessed in 100 patients with FMS randomly assigning to OB (N=40), CBT (N=40), and an attention placebo (social discussion, AP, N=20) treatment groups. In addition, 30 age- and sex-matched Healthy controls (HC) were included for comparison. Surface electromyography (EMG) recorded from the trapezius muscle, blood pressure (BP), heart rate (HR), and skin conductance levels (SCL) were continuously recorded during adaptation and baseline, social conflict, mental arithmetic, and relaxation tasks. Additionally, pain and activity score by Multidimensional Pain Inventory (MPI) were recorded. Assessments were performed pre, post, 6 and 12 months following treatment. The OB and CBT groups reported significant and stable reductions in pain intensity (F(4;102) = 3.51, p<0.01). FMS showed significant lower EMG and elevated HR and SCL compared to the HC prior to treatment (Fs(4,130) > 5.51, ps<0.01) as an expression of lowered physical performance capability. Only, the OB group showed significant changes in EMG and HR at 6 month and 12 month after the treatment. Additionally the activity score was increased 12 month after the operant treatment (t (99) = −2.1, p<0.03). The enhanced muscle tension and decreased HR as well as the increased activity after the operant pain treatment suggest an enhancement of physical performance capability in FMS. Supported by grants of Deutsche Forschungsgemeinschaft to KT (Th 988-1/2), HF (FL 156/26, Clinical Research Unit 107) the Max-Planck-Award for International Cooperation, and from the National Institute of Arthritis and Musculoskeletal and Skin Diseases to DCT (AR44724)