A Sterile family is a couple who has no children by their deliberate choice or because they are biologically infertile. Couples who are childless by chance are not considered to be sterile. The object is to estimate the proportion of sterile couples in Jordan indirectly based on the 1994 population census, by separating the two types of childless couples into sterile and fertile couples. Three methods of fitting a negative binomial distribution to the completed family size data obtained from 1994-population census are investigated. It appeared that the third method gives the best fit. Based on the fitted distribution, the proportion of sterile couples is estimated at 6.1% of all couples. This estimate is much lower than the corresponding estimate of sterile couples in the USA, which was estimated at 11%. The difference between the two can be due to some socio-cultural factors influencing the deliberate choice of couples to have no children. The method of estimation can be applied on other populations.