Multidirectional differentiation of neoplastic cells in uterine MMT is still a subject of controversy. The present study was designed to assess the immunophenotype of 15 uterine MMT paying special attention to the markers of neural (neuroendocrine) differentia­tion. In addition, the same immunohistochemical study was performed on 20 human fetal specimens in order to establish possible relationships between the immunophenotype of MMT and the expression of the corresponding antigens in the fetal tissues of the embryonal female genital tract. Besides the typical immunohistochemical patterns in three cases the epithelial component showed simultaneous coexpression of vimentin and desmin, EMA and cytokeratin, whereas epithelial markers were coexpressed with vimentin in the sarcomatous component of one adenosarcoma. Moreover, both components were immunoreactive to the markers of neural differentiation (PGP 9.5, GFAP, HNK-1, N-CAM, HBA 71). This aberrant expression was not correlated with morphological signs of neural differentiation at either light microscopy or ultrastructural levels. Regarding the analysis of fetal tissues, both epithelial and mesenchymal elements in the fetal genital tract expressed the above­mentioned neural markers at different dates of gestation. The intensity of this expression diminishes as the fetus matures and at the end of antenatal life the immunophenotype characteristic for adult life is established. Taking into consideration the capacity of uterine tissue to reproduce embryonal phenotype during neoplastic transformation, we studied this abnormal immunoprofile and its hypothetic value for the diagnosis and prognosis of MMT.