The responses of plasma prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone were measured in ten women with Sheehan's syndrome after intravenous administration of the appropriate releasing hormones. Growth hormone and cortisol responses to insulin-induced hypoglycemia were also measured. It was found that two patients were biochemically borderline euthyroid and eight were probably hypothyroid in the face of thyroid-stimulating hormone values in the reference range; in two patients thyroid-stimulating hormone response to thyrotropin-releasing hormone was appropriate. In no patient were the minimum prolactin levels achieved, in response to thyroid-releasing hormone as established in reference subjects. Growth hormone response to hypoglycemia was inadequate in all patients and only one patient achieved reference range values of cortisol during hypoglycemia. In six patients fasting LH and FSH were in the reference range and the response to gonadotropin-releasing hormone was adequate and appropriate in eight patients. In light of these findings it is suggested that prolactin response to thyrotropin-releasing hormone administration would be a reliable and simple screening procedure for suspected Sheehan's syndrome.