OBJECTIVE The overlap between symptoms of PTSD and MDD is substantial. PTSD symptoms arise after a traumatic experience and the trauma is present in all of the diagnostic clusters. In individuals who have experienced a trauma a long time before, it is difficult to establish the exact moment of onset of their symptoms in relation to the trauma suffered. We proposed to raise awareness among operators who may encounter this problem, with the aim of providing them with valuable help in order to achieve a correct differential diagnosis. METHODS A sample of subjects suffering from PTSD without comorbidity was assessed to confirm the diagnosis and the severity of post-traumatic symptoms. The Kruskal-Wallis test was used to compare any modifications in the parameters analyzed through the Davidson Trauma Scale with the presence and severity of depressive symptoms as evaluated by the Hamilton-D scale. RESULTS Half of the PSTD patients recruited showed values of HAM-D > 18, although an active Major Depressive Episode was clinically excluded. Symptom of "numbing", despite being different from the apathy experienced in depression, is identified as a depressive symptom by the HAM-D. CONCLUSIONS Giving prevalence to depressive symptoms may be misleading for diagnosis and may ultimately result in inappropriate treatment.