The authors report 17 cases of a right non-recurrent inferior laryngeal n. (NRILN) observed during 15 years of practice of thyroid and parathyroid surgery. In their last two cases, the existence of an aberrant right subclavian a., constantly associated with NRILN, was confirmed by MRI angiography. On the basis of the literature and their own experience, the authors review the incidence of this double anomaly, its embryologic explanation and its anatomic and surgical importance. They stress the diagnostic factors and the therapeutic implications, very different in children and adults, of a particular vascular anomaly whose outcome is little understood.