We examined 4 cases of synovial sarcoma, 3 biphasic-one of which was located in the abdominal wall-and 1 monophasic, in patients between 16 and 54 years. Immunohistochemistry revealed the capacity of these neoplasms to express mesenchymal and epithelial markers, not only in the sarcomatous-like stroma but also in gland-like component. We also found that in the epitheliomorphous cells vimentin positivity had a characteristic basal position whereas EMA and cytocheratins were much more positive in the apical zone. This double positivity could be profitably utilized when the predominance of the gland-like component in a synovial sarcoma requires differential diagnosis from metastatic adenocarcinoma.