Gene products estrogen receptor alpha, progesterone receptor-A, retinoid X receptor alpha, insulin-like growth factor-II, insulin-like growth factor I receptor beta, platelet-derived growth factor, epithelial growth factor receptor, and BCL-2 were examined by immunohistochemistry with the aid of a tissue microarray from 46 hysterectomies with adenomyosis and leiomyomata. With appropriate internal controls, there were significant differences in gene expression between adenomyosis and leiomyomata.