To investigate the hormone response of hypothalamic-pituitary-gonad axis and spermatogenesis in male pituitary stalk interruption syndrome patients by pulsatile GnRH therapy. The hormonal response of the hypothalamic-pituitary-gonad axis was assessed after pulsatile GnRH replacement by measurement of serum T, LH and FSH. A standard seminal fluid analysis was performed in men who could produce an ejaculate.