This article gives the results of a study held on the social representation of endogamy and of its biological consequences on the health of the descendants of Shiite Muslims engaged in endogamous couples. The people studied come from two Lebanese villages. Interviews were held with engaged couples, key informers and a group of mothers. Qualitative analysis of what they said let us identify two models of social representation of endogamous marriages: the safe one and the risky one. As to social representations associated with the origins of the biological consequences of endogamous marriage, the causes could be defined precisely as supernatural, biological, sociobehavioral and environmental. The results of this research show that the endogamous marriage, which is the most frequently practiced in the two villages mentioned above, can only be conceived by means of cultural and socio-economico-political understanding of these two communities.