OBJECTIVE: We examined whether autonomic flexibility to experimentally presented stressors is reduced in somatic symptom disorder (SSD) as this would point to reduced vagal control as a proposed indicator of emotion regulation deficits. METHOD: In this experimental study, the influence of health-related and social stressors on subjective and physiological reactivity was investigated in 29 subjects with SSD without any medical condition SSD(mc-), 33 subjects with SSD with medical condition SSD(mc+) and 32 healthy controls at the age from 18 to 70 years. Self-report and physiological variables were measured before and after/during stressor exposure, using state ratings of symptom intensity, disability, tension and mood, heart rate (HR), and heart rate variability (HRV). RESULTS: Overall, the tension increased and the mood worsened after exposure to stressors compared to pre-exposure. Compared to HC, the two SSD groups showed higher symptom intensity, disability, tension and worse mood. The SSD(mc-) group revealed higher HR than HC (p??????012, d??????0.77). Compared to pre-exposure, symptom impairment increased after social stressor exposure in SSD(mc-) (p??????001, d??????.36). HRV-root mean square of successive differences (RMSSD) only decreased in HC during exposure (p??????003, d??????1.09), not in the SSD groups. The two SSD groups did not differ in their reactivity to stressors. CONCLUSION: HRV in SSD, seems to respond less flexibly to stressors, potentially reflecting overall physiological disturbance through reduced parasympathetic influence on HR. Stress reactivity in SSD(mc-) and SSD(mc+) do not seem to differ.