Abstract                                                                                                                                                                                                                             Adhesion molecules are involved in nerve growth, synaptic plasticity and myelin formation and maintenance process. Neural cell adhesion molecule (CD56 or NCAM) seems to play a crucial role in all the above-mentioned events. Having found polysialylated NCAM increased re-expression on demyelinated axons within multiple sclerosis plaques we assessed soluble NCAM (sNCAM) in sera of patients with various types of peripheral nerve affections – demyelinating, axonal “inflammatory”, axonal metabolic polyneuropathies and healthy controls. These data were compared with the clinical state using Overall Neuropathy Limitations Scale (ONLS) and nerve conduction studies. We found significantly increased sNCAM concentration in demyelinating polyneuropathies in comparison to axonal group and healthy controls as well as significantly increased sNCAM level in axonal group in comparison to healthy subjects. We also found high positive correlation between sNCAM and ONLS and strong negative correlation between sNCAM level and the lowest conduction velocity (Vmin) found in a patient. We conclude that sNCAM might be thought as specific marker of peripheral nerve demyelination and as a sensitive marker of peripheral nerve injuries.