Adnexal tumors of skin are a group of relatively uncommon tumors. Their differential diagnosis is complicated by the fact, that in one lesion different lines of differentiation may be present, i.e. eccrine, apocrine or pilosebaceous. Immunohistochemistry can provide additonal informations on the cellular phenotype. In the present paper fifty-three sweat gland tumors have been investigated by immunohistochemistry in the paraffin section. The usefulness of commonly used 'marker antibodies' (S-100, CEA, Cam 5.2, Vim9(1)) has been challenged by the use of routine material and a comparison to other adnexal, vascular and epidermal tumors of skin (n = 22). Tumors with lumen formations, which express at least Cam 5.2 and CEA are highly suggestive for a differentiation related to the secretory coils of eccrine or to apocrine glands. Lumen forming tumors with the phenotype CEA-positive/ Cam 5.2-negative more closely resemble the eccrine duct. A myoepithelial phenotype is more suggestive, when cells are expressing vimentin and S-100. The histopathology, however, is an essential for the interpretation of immunohistochemical findings.