BACKGROUND: Dissociative symptoms are often seen in patients with mood disorders, but there is little information on possible association with subgroups and temperamental features of these disorders. METHODS: The Dissociative Experience Scale was administered to 85 patients with a DSM-IV Major Depressive Disorder (MDD) or Bipolar-II Disorder (BP-II). Both broad-spectrum dissociation (DES total score) and clearly pathological forms of dissociation (DES-Taxon) were assessed. Temperament was assessed using Akiskal and Mallya;s criteria of Affective Temperaments and the Jenkins Activity Survey (JAS) for Type A Behaviour. RESULTS: Sixty-five patients gave valid answers to DES. The mean DES and DES-T scores were higher in BP-II (16.8 and 12.7 respectively) compared to MDD (9.0 and 5.7); DES odds ratio (OR)=1.58 (95% CI 1.15-2.18) and DES-T OR=1.60 (95% CI 1.14-2.25) using univariate logistic regression analyses. There was no significant difference in DES score in patients with (n=30) and without an affective temperament (n=35): mean (95% CI), 13.5 vs. 10.5 (-7.8 to 1.9), p=0.224. However the subgroup with a cyclothymic temperament (n=18) had higher DES scores (mean (95% CI): 17.8 vs. 9.7 (2.9-13.3), p=0.003), compared to patients without such a temperament. There was no significant difference in DES scores for patients with (n=35) or without (n=28) a Type A behaviour pattern (JAS>0): mean (95% CI) 12. 7 vs. 10.9 (-6.8 to 3.3), p=0.491), but a positive JAS factor S score (speed and impatience subscale) was associated with significantly higher DES scores than a negative S-score: mean (95% CI) 14.9 vs. 9.0 (1.1-10.7), p=0.017), and this was still significant (p=0.005) using multiple linear regression of DES scores vs. the JAS subscale scores. DES-T scores were significantly higher in patients with OCD (n=9) (mean (95% CI) 18.4 vs. 6.6 (6.0-17.7), p<0.001); eating disorder (n=13) (14.0 vs. 6.8 (1.8-12.6), p=0.009), psychotic symptoms during depressions (n=9) (16.6 vs. 6.9 (3.7-15.8), p=0.002), and in those with a history of suicide attempt (n=28) (11.9 vs. 5.4 (2.2-10.8), p=0.003), but only OCD was an independent predictor after multiple linear regression of DES-T scores vs. all co-morbid disorders (p=0.043). LIMITATIONS: The major limitation of the present study is a non-blind evaluation of affective diagnosis and temperaments, and assessment in a non-remission clinical status. CONCLUSIONS: Dissociative symptoms measured with the Dissociative Experience Scale are associated with bipolar features, using formal DSM-IV criteria, cyclothymic temperament and the speed and impatience subscale of the JAS.