Carpal tunnel syndrome is a neurological disease that presented with paresthesias, pain, and numbness in the hand's median nerve compression. Vitamin D was assumed to affect both electrophysiological &clinical gradings, the study aims to assess the correlation between the deficiency of vitamin D and both electrophysiological and clinical gradings. This study was conducted in Ghazi Alhariri Hospital during the period from the first of November/2020 to the twenty-eighth of February/2021, fifty five individuals were referred to as Carpal tunnel syndrome patients, and compared to (55) control individuals, blood samples were withdrawn from the patients (3ml), centrifuged and kept in the freezer (-20°C) until the time of analysis of vitamin D3, Sensory and motor nerve conduction studies of both median and ulnar nerve were done bilaterally. patients were classified electrophysiologically and clinically into two subgroups (mild to moderate) and (severe) groups. The result showed that the differences are not significant in the gender, BMI and vitamin D of the patients versus the control group (p>0.05), the difference of the electrophysiological parameters was not significant between patients with low vitamin D versus those with normal vitamin D (p value>0.05), there was a significant association between the electrophysiological and clinical grading in addition to a significant association between vitamin D level and the clinical grading. Vitamin D deficiency does not affect the electrophysiological parameters while the clinical grading becomes worse with the decrease in its level. The electrophysiological grading is associated with clinical grading.