Objective. To correlate the cross-sectional area of the median nerve proximal and distal to carpal tunnel and the character of nerve lesion — axonotmesis and neurapraxiain in carpal tunnel syndrome. Material and methods. Twenty-six hands with carpal tunnel syndrome and 30 hands of controls were examined. In all cases, median nerve cross-sectional areas were measured using ultrasonography and electromyography. The diagnosis and categorization of carpal tunnel syndrome were based on electrophysiological criteria. In all patients with confirmed carpal tunnel syndrome, needle electromyography of m. abductor pollicis brevis was used. Patients with carpal tunnel syndrome were divided into two groups according to the type of lesion of the median nerve — axonotmesis or neurapraxia. Correlation of ultrasound parameters with the character of the nerve lesion was evaluated. Results and conclusion. Sensitivity and specificity of measurements of cross-sectional area of the median nerve after tunnel in the diagnosis of carpal tunnel nerve lesion by axonotmesis type were estimated as 89% and 85%, respectively. Thresholds of cross-sectional area with respect to the character of lesions of the median nerve were established.