Estrogens have an important function in the natural history of uterine leiomyomata. The human estrogen receptor beta gene (ESR2) has been identified recently and mapped to 14q22-24, a region frequently rearranged in uterine leiomyomata and other benign tumors, including pulmonary chondroid hamartomas and endometrial polyps. Using fluorescence in situ hybridization and radiation hybrid mapping, we map ESR2 within 14q23-24.1, to a region approximately 2 Mb centromeric to the t(12;14) breakpoint in uterine leiomyomata, between markers D14S63 and WI-7536. Two YAC clones, 948B6 and 741H4, contain ESR2. Using RT-PCR, we show that ESR2 is expressed in uterine leiomyomata and pulmonary chondroid hamartomas as well as in normal myometrium. Lack of a direct relationship between rearrangement of 14q23-24 and ESR2 expression suggests that ESR2 is not involved with HMGIC or HMGIY in t(12;14) or t(6;14). However, because of its relatively close physical distance from the characteristic site of rearrangements in 14q23-24, a role for ESR2 in the pathobiology of these tumors warrants future consideration.