Analysis of literature indicates that genetic mechanisms of thyroid tumor development are connected with two main classes of genes: oncogenes whose activation may stimulate tumor growth and anti-oncogenes which acquire oncogenic properties due to the loss of their function through point mutation or deletion. Protooncogene Ras mutation plays a role in the early events in tumor development. Restructuration of Ret and Trk oncogenes, overexpression of Met and Ras point mutations are characteristic for papillary thyroid carcinoma.