Consanguineous marriage has long been a controversial topic, with particular attention focused on adverse health outcomes. Unfortunately, the studies that have been conducted on consanguinity to date have usually lacked control for important sociodemographic variables, such as maternal age and birth intervals, and in estimating specific disease gene frequency, they have ignored the influence of population sub-division. Inadequate attention has also been paid to the social benefits associated with intra-familial marriage, resulting in a biased overall cost-benefit assessment. Worldwide, some 1,000 million people live in countries where 20 to more than 50% of marriages are consanguineous, and large migrant communities from these regions are now resident in Western Europe, North America and Oceania. The need for comprehensive and more balanced investigations into all aspects of consanguineous marriage is pressing and merits a substantial international collaborative research effort.