Sex hormones are known to be associated with increases of melanocytes and melanin production in human skin. However, the expression of estrogen receptor (ERalpha) in melanocytic lesions has been controversial. In 1996, a new subset of estrogen receptor was cloned, and named estrogen receptor beta (ERbeta). We used immunohistochemical staining to characterize the expression of ERalpha and ERbeta in normal skin and in melanocytic lesions. Normal sebaceous glands and hair follicles were positive for ERalpha and ERbeta. Other adnexal structures and constituents in the skin were positive for ERbeta, but not for ERalpha. Melanocytic nevi and malignant melanomas were negative for ERalpha, but both were positive for ERbeta. The ubiquitous expression of ERbeta may play a fundamental role in various normal skin cells and melanocytic tumors.