Objective: determine the incidence of difficult endotracheal intubation in patients who underwent elective thyroid surgery, evaluating the predictive value of the known risk factors and specific risk factors for this population.Material and Methods: retrospective study of 512 patients who underwent elective thyroid surgery, based on anaesthesia medical records. Results: the incidence of difficult endotracheal intubation was 12.7%. All the classic risk factors for difficult endotracheal intubation were greater in the difficult endotracheal intubation group (with a positive predictive relation for Mallampati grade and reduced cervical mobility). The diagnosis of diving or compressive multinodular goiter had a positive predictive value. In 24.6% of patients with difficult airway no risk factor was found for difficult endotracheal intubation which probably corresponds to a false negative group.Conclusions: the presence of anatomical alterations in the airway conditioned by diving or compressive multinodular goiter are predictive factors in difficult endotracheal intubation in thyroid surgery.