Abstract: The discovery of DNA paternity tests has stirred a debate concerning the definition of paternity and whether the grounds for such a definition are legal or biological. According to the classical rules of Islamic law, paternity is established and negated on the basis of a valid marriage. Modern biomedical technology raises the question of whether paternity tests can be the sole basis for paternity, even independently of marriage. Although on the surface this technology seems to challenge the authority of Islamic law in this area, the paper argues that classical Islamic rulings pertaining to paternity issues continue to hold higher authority even in cases of conflict with modern technology-based alternatives. Through closer analysis, the paper traces the emergence of a differentiation in the function of DNA tests between identity and paternity verification. While the former is accepted without reservation, the latter is approved only when it does not violate the rulings of Islamic law.