A regulatory role for estrogen in the growth of salivary gland tumors has been hypothesized. In the current study we attempted to establish whether or not benign and malignant parotid tumor cells express estrogen receptors. Immunohistochemical studies were performed with samples of tissue from 72 patients with benign tumors and 26 patients with malignant tumors originating in the parotid gland. Replicate tissue sections were stained with two sets of reagents specific for the receptors. There was no immunohistochemical evidence for the presence of estrogen receptors in any specimen examined. In contrast, cells in tissue sections from a breast cancer control were consistently positive for estrogen receptor using the same techniques. These observations show that the estrogen receptor concentration in parotid tumors is below the level required for visualization by immunohistochemical techniques. Thus, it is unlikely that this receptor plays a major role in regulating parotid tumor growth.