Seven examples of Clement and Scully's type II uterine tumors resembling ovarian sex cord tumors were studied immunohistochemically with markers of sex cord, steroid cell differentiation (inhibin, O13, A103), or both, and were found to be immunoreactive for one or more of these markers in all cases. There was also constant immunoreactivity for vimentin and for hormone receptors and variable positivity for keratin, actin, and desmin. These findings provide strong evidence for the presence of true sex cord elements in these tumors, the derivation of which remains speculative.