Background Cholesterol is one of the most important components of the myelin sheath. Schwann cells are responsible for myelinization of peripheral nerves. All situations that disrupt cholesterol metabolism in Schwann cells may affect channel dynamics on peripheral axons. Cholesterol entrance into the cell has been impaired due to genetic defects in apoproteins or its receptors in familial dyslipidemia patients. This is why we aimed to study the effects of this possible metabolic impairment on familial dyslipidemia patients. We have been investigated motor and sensorial axonal excitability parameters. Material and methods We have evaluated median nerve motor and sensory axonal excitability parameters of patients diagnosed with familial dyslipidemia or investigated for familial dyslipidemia according to National Lipid Association screening and Simon Broome criteria by using Q-trackS software and compared with control group. Results There was a statistically significant difference in the refractory period in 2 ms (p = 0.0429, p = 0.00281) when the familial dyslipidemia group and control group were compared in terms of both sensory and motor electrophysiological parameters. Conclusions In patients with familial dyslipidemia, we have found that the refractory period is shorter than the control group in both sensory and motor electrophysiological parameters of the median nerve. This finding may suggest that the median nerve axons in these patients are hyperpolarized state than normal. This study is supported by TUBITAK.