Consanguineous marriage has had considerable attention as a causative factor in the prevalence of genetic disorders. Iran, with its majority Muslim population, has a high rate of consanguineous marriage. In Iranian tradition, first cousin marriage is an acceptable and appreciated custom. However, there seems to be no encouragement of consanguineous marriage in the Islamic context; it is merely mentioned as a traditional and common custom. This paper may help medical professionals providing premarital genetic counselling, who are regularly asked about consanguineous marriage, especially in Islamic communities. Increased public awareness via the mass media would seem to be a priority.