Daily early morning urine samples were collected from women receiving donor artificial insemination and were evaluated for estrone conjugates, pregnanediol-3-glucuronide, and human chorionic gonadotropin. All hormone concentrations in urine were indexed by creatinine levels and expressed as the concentration of hormone per milligram creatinine. Composite profiles of 23 women who conceived normal full-term pregnancies were compared with composite profiles obtained from 11 of the same women during nonconception cycles. The endocrine profiles of seven pregnancies that spontaneously aborted and two ectopic pregnancies were also evaluated retrospectively. The combined application of these three urinary hormone indices provides a practical approach for prospective monitoring of the major hormone dynamics during ovulation and implantation and during relatively infrequent events such as spontaneous abortion and ectopic pregnancy. The rise of estrone conjugates which precedes detectable increases of urinary human chorionic gonadotropin at the time of implantation appears to be an early indicator of implantation and may prove to be the best method for detection of occult pregnancy. This method is also suitable for monitoring early pregnancy when exogenous gonadotropins have been employed, as in embryo transfer following in vitro fertilization.