A granulosa theca cell tumor was found in a 10-month-old girl with precocious puberty. Steroid hormone receptors were measured in fractionated tumor cells. Estrogen and progesterone receptors were measured in the cytosol, and estrogen receptors were measured in the nuclear fraction of the tumor. Although high affinity (Kd 0.4 nM) progesterone receptors were present in the cytosol of this tumor-54 fmole/mg protein-no cytosolic estradiol receptors could be detected; however, these receptors were found to be tightly bound to the nuclear fraction of the tumor. The nuclear protein had lower apparent Kd for the hormones-5.4 nM. This tumor produced and released various steroid hormones. The plasma steroid levels before removal of the tumor were 1,200 pg/ml for estradiol, 350 pg/ml for testosterone, and 5 ng/ml for progesterone. All these steroid hormones declined postoperatively to undetectable levels, with total remission of pubertal signs. Plasma-dehydroepiandrosterone, prolactin, and gonadotropin levels were in the normal range before and after surgery. These results suggest that cytosolic progesterone receptor as an estrogenic marker and/or nuclear estrogen receptors may predict the hormonal dependency of these estrogen-producing tumors.