Sclerosing stromal tumors (SSTs) are uncommon ovarian neoplasms of the sex cord-stromal category, that usually occur below 30 years of age. In the present study three cases of SSTs, diagnosed during the last eight years in our hospital, were examined immunohistochemically with stains for estrogen receptors, alpha and beta, progesterone receptors, and stains for markers that have been reported to be of use in the diagnosis of sex cord-stromal tumors. They were also examined by fluoresence in situ hybridization (FISH) for the presence of trisomy 12 and 7. Positivity for ERbeta was observed in a significantly larger number of cells than ERalpha. Positivity for calretinin and A103 was observed in tumor cells. In two cases 20-30% of the nuclei showed trisomy 12. No aberration of chromosome 7 was detected. The finding of increased ERbeta expression needs further investigation.