Thirty-eight patients with primary amenorrhea were evaluated by the administration of luteinizing hormone releasing hormone (LHRH). The LHRH stimulation test was not helpful in differentiating those patients who will proceed to normal menses from those who will continue to have prolonged dysfunction. Similar responses were observed in patients with different pathology, which indicates that the LHRH test must be utilized in conjunction with a carefully planned evaluation if it is to he useful in differentiating a hypothalamic from a pituitary defect. The finding of a patient w*ith hypergonadotropism by serum radioimmunoassay and negative gonadotropins by bioassay suggests that the radioimmunoassay may detect a biologically inactive molecule and indicates that both assays are essential in the evaluation of primary amenorrhea.