Many fundamental processes involve protein–protein interactions. Recent advances in technology make it possible to perform large–scale, genome–wide interaction mapping experiments that result in an always increasing amount of data. Protein–protein interaction databases are thus becoming a major resource for investigating biological networks and pathways. In this chapter we describe the Molecular INTeraction database (MINT). The MINT database aims at storing, in a structured format, information about protein–protein interactions (PPIs) by extracting experimental details from work published in peer–reviewed journals.