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Previous studies of tumors mainly focused on the abnormal proliferation of tumor cells, as the main force of this nosological entity, and on their differentiation into the new pathological cell types. The tumor stroma, as integral component of each neoplasm, is still not sufficiently examin ed and und ersto od . B earing in min d that b asal c ell c arcinoma o f t he s kin (BCCS) a re stromal dependent tumors, the aim of our research was to examine the microtopographical distribution of the antigens Ep-CAM, CD3 4 and CD9 0 in the stroma o f t he t umor r eg ions and peritumoral skin in different histopathological types of BCCS (superficial, solid/cystic, nodular, infiltrative, basosquamous). The material consisted of samples of skin and subcutaneous tissue obtained after surgery, which were routinely processed to paraffin tissue blocks, which were cut on microtome in order to obtain thin paraffin tissue sections. The tissue sections were stained histochemically with hematoxylin and eosin and with modified Movat’s pentachrome staining, as well as immunohistochemically on Ep-CAM, CD34 and CD90, before being submitted to descriptive micromophological analysis. Cells in tumor nests of examined BCCS do not express antigens CD34 and CD90, while the immunoreactivity toward the antigen Ep-CAM is present on the membrane of these cells in all examined types of BCCS, with the tendency of the decrease or complete loss of this reaction in places of squamous citodifferentiation in tumor nests. Tumor stroma of examined BCCS shows importantly higher level of immunohistochemical reactivity toward the antigen CD90 compared to CD34 antigen. With the increase of biological aggressiveness of BCCS, it is noticed that fibroblastoid cells of tumor stroma grow in size and number. CD34 antigen is not present in the perinodular and internodular compartments of tumor stroma, with the exception of nodular BCCS. Immunohistochemical reactivity toward the antigen CD90 is seen in the whole tumor stroma, but the decrease of this immunoreactivity is noticed in infiltrative forms of BCCS (nodular, infiltrative, basosquamous). The narrow zone of juxtatumoral region shows high degree of immunopositivity on CD34 and CD90. The intensity of this immunohistochemical reactivity decreases abruptly toward the periphery, to the level of intensity that dominates in the rest of skin of the biopsy specimen. In the differentiated types of BCCS (superficial, solid/cystic) this zone of transformation is composed of atrophic/compressed fibrous connective tissue of the reticular dermis, while in nodular, infiltrative and basosquamous BCCS this zone is wider with the tendency of decrease of its structure and organization. Normal epithelial structures of skin, epidermis and epithelium of skin appendages are CD34and CD90 immunonegative. The exceptions are the cells of outer root sheath of non vellus hairs, which show strong CD34 immunoreactivity. Epithelial cells of secreting portions of eccrine sweat glands show immunoreactivity toward the antigen Ep-CAM on their membranes, and Ep- CAM is also expressed on the membranes of the cells of the outer root sheath of hair follicle, in the parts of peritumoral skin closer to the region of tumor. CD34 immunoreactive fibroblastoid cells are seen in periadnexal dermis around the secreting portions of eccrine sweat glands and sebaceous glands, around the hair follicle isthmus and infundibulum, sebaceous duct, as well as in the perimysium of arrector pili muscle. The fibroblasts of the interfascicular zone of reticular dermis show intensive immunohistochemical reactivity toward CD34 antigen, but weak or absent CD90 expression. The fibroblasts of the periadnexal dermis are CD90 immunoreactive around the secreting portions of the eccrine sweat glands, sebaceous ducts and around the hair follicle isthmus, while much weaker or even absent CD90 immunoreactivity can be seen around the sebaceous glands, hair follicle papilla and excreting ducts of eccrine sweat glands.