The total content of 17-beta estradiol and progesterone receptors in human uterine leiomyoma and normal myometrium in a Caucasian population was determined. Estrogen receptor concentrations in leiomyoma and myometrium were not significantly different (p = 0.1401). The concentration of progesterone receptors in leiomyoma was higher than in myometrium (p = 0.0303). Negroid and Caucasian ethnic groups did not differ with respect to estrogen (p = 0.7040) or progesterone (p =0.8494) receptor concentrations in leiomyoma, but estrogen (p < 0.005) and progesterone (p < 0.005) receptor concentrations in normal myometrium were significantly higher in Caucasian than in negroid patients. Leiomyoma in negroid and Caucasian patients appears to be histologically similar, but the biochemical pathway of its pathogenesis seems to differ. Genetic predisposition probably acts as an initiation factor in the myometrium of both ethnic groups, then estrogen receptor levels in negroids and alterations in steroid metabolism in Caucasians promote the growth of leiomyoma.