Uterine leiomyoma (UL) is a benign and most common tumor that affects 20-45% of women of fertile age. In this study, we analyzed the MED12 second exon nucleotide sequence from 15 DNA samples extracted from LM of 15 subjects with uterine leiomyoma and 15 DNA samples extracted from peripheral blood leukocytes of the same female subjects. It was shown that somatic mutations in the MED12 gene occur in 73% of cases with deletions of varying sizes and missense mutations being most common at codon 44. Mutations in the MED12 gene could play an indirect role in leiomyoma progression by modifying the activity of other genes that encode proteins involved in growth and tumor progression.