In nonclinical samples, childhood trauma (CT) has been found to negatively affect temperament/character traits. In major depressive disorder (MDD) and bipolar disorder (BD), abnormal personality traits have been found to impair clinical course/treatment outcome. Although a link between CT and MDD/BD is firmly established, no previous studies explored the relationship between CT and temperament/character in these populations. We investigated this issue in a preliminary sample of inpatients with MDD (n = 29) or BD (n = 50). We assessed CT (sexual/physical/emotional abuse, physical/emotional neglect) (Childhood Trauma Questionnaire), personality traits (Temperament and Character Inventory-Revised version), and illness severity (Brief Psychiatric Rating Scale). We found significant (p < 0.01) associations between emotional neglect, emotional abuse, physical neglect, and low self-directedness (SD). Potential underlying mechanisms are discussed. Because low SD has been previously associated with illness severity and poor outcome, the relationship between CT and low SD might partly explain the well-known negative impact of CT on course and outcome of MDD/BD.