Under analysis were results of genetic investigations of 105 patients with thyroid cancer (TC) treated from 2004 through 2007 in the St. Petersburg City Center of surgery and oncology of the endocrine system organs. The patients' age was from 17 to 80 years (mean age 51.6 +/- 1.9 years). The influence of functional variants of matrix metalloproteinase genes in TC was determined. A reliable correlation was noted between certain gene markers and TC patients' age. An association was revealed between matrix metalloproteinase-3 5A (more active allele) and size of the tumor. A reliably decreased frequency of hyperactive genotype MMP-1 2G was detected in a group of women with metastatic forms of papillary cancer as compared with patients without metastases. It was shown that MMP genes could be a substantial factor of slowing down the rate of malignant growth and invasive properties of cancer of the thyroid gland.