3DIANA is a web based environment designed to integrate bioinformatics-like information for the analysis of protein interactions and quaternary structure modellling. The first version of the application introduces the use of molecular interaction data to evaluate potential binding domains between proteins. Protein domains are defined according the Pfam classification and calculated with the HMMER package. Domain-Domain Interaction scores are computed with DIMERO approach. Also Domain-Domain Interaction templates collected from 3DID database are integrated in order to identify potential domain binding sites in protein structures and to provide a set of structural templates for protein docking.