Aim: The aim of this paper is to test the validity of the trauma axis of a dimensional model for diagnosis and treatment indication of trauma-related and dissociative disorders. The central question is: is the (trans-diagnostic) continuum of trauma-related and dissociative disorders related to the severity in reported traumatization: a dose-response relationship? A sample of one hundred and fifty consecutive patients, indicated for treatment in either a trauma-related disorders or a personality disorders treatment program, was systematically assessed on trauma-related disorders, dissociative disorders, and childhood trauma, using structured interviews. We constructed a ‘trauma-diagnosis severity score’ by classifying patients according to their most severe disorder (ranging from none, (chronic) posttraumatic stress disorder (PTSD), complex PTSD to dissociative disorder not otherwise specified, and finally dissociative identity disorder, in ascending order). The observed correlation (rs = .54) between reported trauma severity and this trauma-diagnosis severity score indicates that retrospectively reported trauma severity in child- and adulthood is strongly associated with more severe pathology. Trauma-related and dissociative disorders may be considered as forming a continuum, ranging from less to more extreme severity. The findings support the significance of the trauma-axis of the proposed dimensional model.