The objective of the present study was to evaluate the pharmacokinetics of human chorionic gonadotropin (hCG) following different regimens of subcutaneous and intramuscular single-dose administration. Two hypogonadotropic hypogonadal volunteers received hCG injections without prior ovarian stimulation. The regimens included a single dose of 10,000 IU hCG either subcutaneously or intramuscularly, or 5000 IU hCG intramuscularly. Serum beta-hCG concentrations were measured periodically up to 13 days after hCG administration. Each of the three regimens exhibit a similar pharmacokinetic profile and the highest serum beta-hCG concentrations were achieved with a dose of 10,000 IU administered subcutaneously. Seven days after hCG administration beta-hCG was detectable only after subcutaneous or intramuscular administration of 10,000 IU, but not after a single intramuscular injection of 5000 IU. From the preliminary results of the study it is suggested that a single intramuscular dose of 5000 IU hCG might be sufficient to trigger ovulation, but for luteal-phase support a higher dose may be needed. Subcutaneous administration of hCG for the induction of ovulation or luteal-phase support in gonadotropin-induced cycles is feasible and might offer a better tolerance and cost-effectiveness of infertility treatments, leading to their further simplification.