In our investigation we showed, that the thickness of the epidermis is increased in a mixed group of CRPS-patients as well as in patients with a normal wound healing after fractur of the forearm compared to a healthy control group. This finding indicates the pathophysiological relevance of the inert immune system, where the keratinocytes pertain to, even in chronic stage of CRPS. This finding is new. Former studies showed, that the keratinocyte layer increases in the acute stage and decreases in the chronic stage. The thickening of epidermis in skin of fracture-patients can be explained by normal healing process. This finding is interesting as well, because this effect persists over time. The IENFD showed no difference between the patient groups. The clinical examination during QST-testing generated indications of reduced pain thresholds for thermal and mechanical stimuli. Detection thresholds were unchanged. This findings matches to the non-significant findings of IENFD and points to a process of sensitization in course of pain disease. A modulation of the mechano-sensitive receptors, by mediators like NGF, CGRP or Substance P and others could be an explanation for our findings. There are no findings for an involvement of CD-45-positive leukocytes in the inflammatory signs in course of CRPS, because there was no significant difference between the examined groups. Our results are helpful to consider CRPS in context of pathological healing of the initial trauma.