Uterine fibroids are the most common benign tumor of the female genital tract. Their epidemiology is probably highly underestimated because a high percentage of them are in the asymptomatic stage. The etiology of fibroids and their biology are still poorly understood, although steroid ovarian hormones, both estrogen and progestins, have played an important role in etiopathogenesis of this disease. Also no single candidate gene has been detected for commonly occurring uterine fibroids. Cytogenetic abnormalities, particularly translocation, duplication and deletions of chromosome 7, which are found in up to 50% of fibroid specimens, seem to play an important role during abnormal transformation of uterus smooth muscle. The key regulators that transform normal uterine tissue to fibroids are growth factors (VEGF, TGF, PDGF, etc.), angiogenesis and the process of apoptosis. In this review, current knowledge about molecular and cytogenetic evidence on fibroid development is presented.