We report the concentrations of estradiol and progesterone receptors found in the tumor tissue of 5 patients with leiomyosarcoma, 4 of uterine and one of ventricular origin, and of 5 patients with uterine or ovarian carcinosarcoma. Steroid receptor positive and negative tumors were present in both groups of sarcoma. One uterine leiomyosarcoma had a high concentration of estradiol and progesterone receptors, 37 fmoles/mg protein and 156 fmoles/mg protein, respectively. We suggest that steroid receptors should be analysed in all gynecologic sarcomas.