Uterine myomas represent one of the most common female pathologies. Uterine smooth muscle myomas or fibromas are benign tumours which respond to hormones and their etiology induces wide interest. The myomas were found to contain aromatase and, in addition, cells of the myomas were found to synthesize estrogen. This study was conducted on patients with the myomas, in either generative age or in the perimenopausal period. Expression of aromatase was detected in patients of various age, with large or small uterine myomas, using an immunohistochemical technique. In addition expression of the enzyme was examined at the periphery of every myoma.