PrePPI is a database of predicted and experimentally determined protein-protein interactions (PPI) for the human proteome. Predicted interactions in the database are determined using a Bayesian framework that combines structural, functional, evolutionary and expression information. Currently, PrePPI contains 1.35 million PPIs for ~85% of the human proteome. The PrePPI database also contains experimentally determined interactions compiled from a set of publicly available databases that curate interactions from the literature, e.g., DIP, IntAct, HPRD, etc. Please refer to 'Structure-based prediction of protein-protein interactions on a genome-wide scale (Nature 490, 556–560)' and 'PrePPI: a structure-informed database of protein-protein interactions (NAR 41, D828-33)' for details of the prediction method and the database.