There are couples with unmet family planning needs and couples who do not use any modern method, yet they desire to space or avoid pregnancies. Many of them look for safe and effective options like the natural family planning methods. The Billings Ovulation Method based on single index cervical mucus parameter is one such option. The present multicentre trial conducted in India has shown an encouraging use-effectiveness of the method, indicating method failure as low as 1.5 +/- 0.3 and use-failure 15.9 +/- 0.8 per 100 users at 21 months. The method continuation rates have also been as high as 88.3/100 users at 6 months and 52.0/100 users at 21 months.