The study of the thyroid veins has not received an investigation as extensive as the thyroid arteries and laryngeal nerves did in relation to thyroid surgery. Of the three veins pedicles of the gland the middle is far the least studied. This vein is inconstant and is the first vascular element of the gland that must be sectioned before the medial lobe is dislocated to evaluate its posterior relationships. His injury can cause intraoperative bleeding, making it difficult to identify the inferior laryngeal nerve and the parathyroid glands, proximal to it. A descriptive cross-sectional study was carried out evaluating the presence, number, symmetricity and association of the middle thyroid vein with variables such as age and sex of the patient, as well as the hyperfunctionality of the gland and the presence of the Zuckerkandl tubercle in 100 total thyroidectomies undergoing at the National Cancer Institute and the ENT Service of the Social Security Institute ́s Central Hospital. The overall prevalence of the middle thyroid vein was 74%. In the right lobe the vein appeared in 60% while in the left lobe in 53 %. Double middle thyroid vein was found in 4 patients, in one of them it was bilateral. The highest percentage of the middle thyroid veins originated in the middle third of the lobe, 72 % on the right and 70% on the left side. No association was found between the presence of the vain and age and sex, the state of glandular hyperfunction, as well as the presence of Zuckerkandl tubercle.