The n. laryngeus non-recurrens is a rare anatomical variant encountered in thyroid surgery: less frequently than in 1% on the right side and quite exceptionally on the left side. The authors describe in a case-record their own experience with this developmental abnormality and discuss its embryogenetic, anatomical and clinical aspects. They draw attention to the possible preoperative detection of the n. laryngeus non-recurrens by Doppler ultrasonography which visu- alizes an abnormal course of the right subclavian artery.

        Key words: n. laryngeus non-recurrens, subclavian artery, ultrasonography.