Estrogen receptors (ER) are members of the nuclear receptor superfamily of ligand-activated transcription factors and mediate the effects of estrogen on target tissues. ERalpha was the first estrogen receptor to be characterized, and ERbeta was identified ten years later. The role of ERbeta in breast cancer pathobiology is largely unknown because specific antibodies have not been available until recently. The purpose of this study was to explore the expression of ERbeta in breast neoplasms and to correlate it with ERalpha and prognosis. ERa and ERbeta expression was monitored immunohistochemically in 59 breast carcinomas. We found no correlation between ERalpha and ERbeta expression, between ERbeta expression and the known prognostic indicators such as tumor size, grade or lymph node status, or between ERbeta expression and survival. Our findings contribute to the better understanding of the role of ERbeta in breast cancer.