In order to evaluate the efficacy and safety of recombinant human follicle stimulating hormone (r-hFSH) in combination with urinary human chorionic gonadotrophin (HCG) to induce spermatogenesis and fertility in gonadotrophin-deficient men, we conducted a prospective, open, non-comparative multicentre study in two Australian academic medical centres. Ten men with gonadotrophin deficiency requiring induction of spermatogenesis and fertility were treated with HCG for 3-6 months followed by the s.c. self-administration of injections of r-hFSH in combination with HCG for 18 months. Among the eight men who commenced r-hFSH treatment, seven demonstrated sperm output at a median of 6 months and five achieved the target sperm output of 1. 5x10(6) per ml at a median of 9 months of FSH treatment. Mean testicular volume increased by 4.2 ml during FSH treatment. Three men produced pregnancies in their partners, two of which resulted in the birth of healthy babies and a third patient's partner had a miscarriage. We conclude that r-hFSH is well tolerated and effective in inducing testis growth, spermatogenesis and fertility in gonadotrophin-deficient men. The efficacy of r-hFSH seems comparable with urinary FSH at restoring normal fertility in gonadotrophin-deficient men.