The aim of this study was to evaluate the effect of the agonistic LRH analogue (D-Trp6-LRH) on LH, FSH and prolactin secretion, and its possible efficacy in female patients with anorexia nervosa. The study included 18 female patients with anorexia nervosa and 7 healthy women in the same age group. The patients with anorexia nervosa were divided into two groups of 9 women each. The first group consisted of patients in the weight loss phase of the disorder and the second of 9 women who had achieved normal body weight. Additionally, in 6 women with anorexia nervosa serum LH concentration was determined in response to native LRH before and 14 days after the treatment with D-Trp6\x=req-\ LRH.Serum LH, FSH, prolactin concentrations were determined before and 5, 10, 24 and 48 h after administration of D-Trp6-LRH in a dose of 5 \g=m\g. The serum LH response to D-Trp6-LRH in the second group did not differ from that of the control group. However, in women with anorexia nervosa in the weight loss phase, LH release in response to administration of the analogue was significantly lower. FSH release after LRH analogue administration in both groups of patients with anorexia nervosa did not differ from that in the control group. The increased LH secretion in response to native LRH after treatment indicates that D-Trp6-LRH in low doses did not inhibit pituitary responsiveness. A dose of 5 \ g=m\ g of D-Trp6-LRH was administered in a therapeutic regimen every 48 h from 1 to 3 months to 7 of 9 patients with anorexia nervosa who exhibited amenorrhoea in spite of normalization of body weight. All the patients treated with the analogue resumed menstruation. The results of this study suggest that D-Trp6-LRH may be of value in the treatment of amenorrhoea in women with anorexia nervosa.