The purpose of this paper is to determine what factor affect trust in scientists and food manufacturers, and to examine how trust in these institutions affects public support for biotechnology. Data from the U.S. Biotechnology Study reveal that benefits from biotechnology and expectations of trustworthiness are correlated with trust in scientists, but benefits and costs of biotechnology, and expectations of trustworthiness and competence of biotechnology institutions, are important determinants of trust in food manufacturers. The data also reveal that trust in scientists and food manufacturers has a large and important effect on public support for biotechnology, but trust in scientists is more important for public support than trust in food manufacturers.