Pulsatile gonadotropin-releasing hormone (GnRH) may induce spermatogenesis in most patients with congenital hypogonadotropic hypogonadism (CHH) by stimulating gonadotropin production,while the predictors for a pituitary response to pulsatile GnRH therapy were rarely investigated.Therefore,the aim of our study is to investigate predictors of the pituitary response to pulsatile GnRH therapy.This retrospective cohort study included 82 CHH patients who received subcutaneous pulsatile GnRH therapy for at least 1 month.Patients were categorized into poor or normal luteinizing hormone (LH) response subgroups according to their LH level (LH ＜2 IU I-1 or LH ≥2 IU I-1) 1 month into pulsatile GnRH therapy.Gonadotropin and testosterone levels,testicular size,and sperm count were compared between the two subgroups before and after GnRH therapy.Among all patients,LH increased from 0.4 ± 0.5 IU I-1 to 7.5 ± 4.4 IU I-1 and follicle-stimulating hormone (FSH) increased from 1.1 ± 0.9 IU I-1 to 8.8 ± 5.3 IU I-1.A Cox regression analysis showed that basal testosterone level (β =0.252,P =0.029) and triptorelin-stimulated FSH6omin (β =0.518,P=0.01) were two favorable predictors for pituitary response to GnRH therapy.Nine patients (9/82,11.0％) with low LH response to GnRH therapy were classified into the poor LH response subgroup.After pulsatile GnRH therapy,total serum testosterone level was 39 ± 28 ng dl-1 versus 248 ± 158 ng dl-1 (P =0.001),and testicular size was 4.0 ± 3.1 ml versus 7.9 ± 4.5 ml (P =0.005)in the poor and normal LH response subgroups,respectively.It is concluded that higher levels of triptorelin-stimulated FSH60min and basal total serum testosterone are favorable predictors of pituitary LH response to GnRH therapy.