Objective — to study the clinical and morphological features of leiomyoma of the corpus uteri in early reproductive-aged women, to investigate the expression of estrogen and progesterone receptors, to determine the proliferative index, and to calculate capillaries in the tumor nodules. Material and methods. Immunohistochemical examination of 20 removed leiomyoma nodules (all the women had undergone myomectomy in the follicular phase of their menstrual cycle) was performed in eight 24—30-year-old normally built patients with no history of deliveries and abortions. Three-four tumor samples from each nodule and the fragments of the adjacent myometrium, as well as the expression of estrogen and progesterone, Ki-67, and CD31 receptors were examined. The expression of estrogen and progesterone receptors was estimated with the semiquantitative method according to the histochemical scoring system. The intensity of expression of CD31 receptors was separately measured using a three-point scale; the proliferation index — Ki-67 expression was determined calculating varying positively stained nuclei per 100 nuclei. Results. The leiomyoma cells versus the adjacent unchanged myometrium displayed the higher expression of estrogen and progesterone receptors; in this case the expression of progesterone receptors was greater than that of estrogen receptors; and proliferative activity (Ki-67) was found only in leiomyoma and absent in the intact myometrium. Vascularization was variable in both the tumor and the intact myometrium; the most pronounced expression of progesterone receptors was attended by a large number of capillaries in the tissue tumor, which was coupled with the higher cell proliferation index. Conclusion. The accumulation of actual material on the molecular bases of leiomyoma development will contribute to the elaboration of rational therapy and surgery for this tumor. The authors declare no conflicts of interest.