The authors review 274 cases of Merkel's cells tumor reported in literature and present one case they personally observed. This kind of neoplasm develops itself inside the derma without involving the epidermidis and shows an aggressive biological behaviour. The authors describe its anatomopathologic characteristics and underline the importance of the immunohistochemistry particularly for a differential diagnosis with respect to lymphoma, amelanotic melanoma and the scarcely differentiated metastatic carcinoma. Undoubtedly the surgical treatment is to be preferred. It consists of the removal of the primitive lesion together with a preventive regional lymphadenectomy. Radio and chemotherapy still don't play a standard role, their results are anyway encouraging even if not well defined up to now. These therapies are used in several ways: together with surgery in case of local relapses or metastasis or as sole treatment. In consideration of the small number of available data, we can finally state that Merkel's cells tumor must be further studied in order to come to a certain definition of this neoplasm from a histogenetic and anatomopathologic point of view and, above all, to find out a treatment able to reduce the high mortality rate that still today characterizes the prognosis.