The effects of hysterectomy on several hormone-dependent behaviors and on neural estrogen and progestin receptors were studied in a series of experiments in rats. Ovariectomized-hysterectomized (OH) rats given sequential treatments with 2 yg estradiol benzoate (EB) and .5 mg progesterone (P) showed significantly higher lordosis quotients than ovariectomized (OV) rats in two tests, one and two weeks after surgery. To test whether the effects of hysterectomy persist, 3 groups of OV and OH rats received weekly injections of EB, EB plus P, or sesame oil vehicle for 4 weeks, were then given 2 yg EB followed 24 hr later by .5 mg P and tested for receptivity. Only the OH animals that had received hormone treatments for 4 weeks showed a significantly higher lordosis score than OV animals. The effects of hysterectomy on food intake, body weight gain and running wheel activity were also tested.