The Negatome is a collection of protein and domain pairs which are unlikely engaged in direct physical interactions. The database currently contains experimentally supported non interacting protein pairs derived from two distinct sources: by manual curation of literature and by analysing protein complexes from the PDB. More stringent lists of non interacting pairs were derived from these two datasets by excluding interactions from IntAct. It can be used to evaluate newly derived experimental interactions. The Negatome is much less biased towards functionally dissimilar proteins than the negative data derived by randomly selecting proteins from different cellular locations. Thus, the negatome is complementary to such random data for training protein interaction prediction algorithms.