Systematic reviews of case-control studies demonstrated an association between self-reported childhood sexual and physical abuse and fibromyalgia syndrome (FMS). We tested in a case-control study if the association of self-reported childhood maltreatments in childhood and in adult FMS-patients is attributable to depression.All consecutive patients diagnosed with FMS of two clinical centres were included into the study from January to June 2011. Randomly selected age- and sex-matched controls from a representative survey of the general German population were used as controls. Childhood maltreatments were assessed by the German version of the Childhood Trauma Questionnaire CTQ and depression by the two-item depression scale of the German version of the Patient Health Questionnaire PHQ-4. The scores of the five CTQ-subscales were compared between FMS-patients and controls using analysis of covariance adjusting for depressed mood.153 FMS-patients (87.6% women; mean age 50.3 years) and 153 age- and sex matched participants of the general population were included. The comparison between FMS-patients and population controls, adjusted for depressed mood, demonstrated a significant group difference for emotional (p<0.001), and sexual abuse (p=0.01). Depressed mood fully accounted for group difference in physical abuse (p=0.01) and in emotional neglect (p<0.001). Depressed mood partially accounted for group difference in emotional abuse (p<0.001), but did not account for group difference in sexual abuse (p=0.10).Reports of FMS-patients some on childhood maltreatments were biased by depressed mood. However, the difference in self-reported childhood sexual abuse between adult FMS-patients and population controls was not attributable to depression.