Affect regulation is often compromised as a result of early life interpersonal traumatization and disruption in caregiving relationships like in situations where the caretaker is emotionally, sexually or physically abusing the child. Prior studies suggest a clear relationship between early childhood attachment-related psychological trauma and affect dysregulation. We evaluated the relationship of retrospectively recalled childhood traumatization by primary caretaker(s) (TPC) and affect dysregulation in 472 adult psychiatric patients diagnosed with borderline personality disorder (BPD), somatoform disorder (SoD), both BPD and SoD, or disorders other than BPD or SoD, using the Bermond-Vorst Alexithymia Questionnaire, the self-report version of the Structured Interview for Disorders of Extreme Stress, the Self-Rating Inventory for Posttraumatic Stress Disorder (SRIP) and the Traumatic Experiences Checklist. Almost two-thirds of participants reported having experienced childhood TPC, ranging from approximately 50% of patients with SoD or other psychiatric disorders to more than 75% of patients with comorbid BPD+SoD. Underregulation of affect was associated with emotional TPC and TPC occurring in developmental epoch 0-6 years. Over-regulation of affect was associated with physical TPC. Childhood trauma by a primary caretaker is prevalent among psychiatric patients, particularly those with BPD, and differentially associated with underand over-regulation of affect depending on the type of traumatic exposure.