The need to identify a reliable ovulation predictor has received attention by the scientific community in recent years. For couples practicing natural family planning, a more precise identification of the fertile phase would be a welcome adjunct to their method. A home ovarian monitor invented by Professor J. B. Brown of Melbourne, Australia, enables couples to measure the principal urinary metabolite of ovarian estrogen and progesterone. The charted results reveal the hormonal pattern of the menstrual cycle and thus identify the beginning, peak, and end of the fertile period. A study involving 21 couples was conducted with the purpose of assessing overall acceptability, including ease of use, motivation, and client satisfaction. At the completion of the study, 12 couples indicated a high degree of motivation and satisfaction with the monitor. None reported difficulty with the test procedure. Increased confidence in natural family planning was cited as the most positive evaluation and the time required to perform the test, as the most negative.