OBJECTIVE: This study investigates the prevalence of different types of childhood adversities (CA) and posttraumatic stress disorder (PTSD) in female patients with Fibromyalgia or Chronic Widespread Pain (FM/CWP) compared to patients with Functional Dyspepsia (FD) and achalasia. In FM/CWP, we also investigated the association between CA and PTSD on the one hand and pain severity on the other. METHODS: Patient samples consisted of 154 female FM/CWP, 83 female FD and 53 female achalasia patients consecutively recruited from a tertiary care hospital. Well-validated self-report questionnaires were used to investigate CA and PTSD. RESULTS: Forty-nine per cent of FM/CWP patients reported at least 1 type of CA, compared to 39.7% of FD patients and 23.4% of achalasia patients (p < 0.01). The prevalence of CA did not differ significantly between FM/CWP and FD, but both groups had a higher prevalence of CA compared to both achalasia and healthy controls (p < 0.01). FM/CWP patients were six times more likely to report PTSD than both FD (p < 0.001) and achalasia (p < 0.001) patients. CONCLUSION: In FM/CWP, PTSD comorbidity, but not CA, was associated with self-reported pain severity and PTSD severity mediated the relationship between CA and pain severity. In summary, the prevalence of CA is higher in FM/CWP compared to achalasia, but similar to FD. However, PTSD is more prevalent in FM/CWP compared to FD and associated with higher pain intensity in FM/CWP. SIGNIFICANCE: As expected and has been shown in other functional disorders, we found elevated levels of childhood adversity in FM/CWP patients. Results of this study however suggest that the impact of childhood adversity (i.e. whether such events have led to the development of PTSD symptoms), rather than the mere presence of such adversity, is of crucial importance in FM/CWP patients. Screening for PTSD symptoms should be an essential part of the assessment process in patients suffering from FM/CWP, and both prevention and intervention efforts should take into account PTSD symptoms and their impact on pain severity and general functioning.