The Institute for Systems Biology (ISB) is a non-profit research institution, located in Seattle, Washington, United States. Leroy Hood co-founded the Institute with Alan Aderem and Ruedi Aebersold in 2000.

As its name suggests, the ISB concentrates on systems biology, the study of relationships and interactions between various parts of biological systems. The ISB is also notable for advocating an interdisciplinary approach to biological research.

The ISB has been involved in several high-profile research projects, including the NHLBI Seattle Proteome Center and the Center for Inquiry Science.

In late 2005, the ISB began to emphasize the application of systems biology to P4 medicine, the development of techniques for predicting and preventing disease, possibly before the patient knows they are "sick."