Chilibot was used to retrieve information about 770 pairs of known protein interactions obtained from the Database of Interacting Proteins (DIP). A total of 702 relationships were found (recall = 91.2%). Relationships were undetectable (n = 68) for the following reasons: 21 (30.8%) occurred when a specific member of the protein family (e.g. cdc25a) was recorded in DIP, yet only the general family name (e.g. cdc25) appeared in abstracts; 18 (26.5%) were due to synonyms present in abstracts and not in Chilibot's dictionary of nomenclature; 15 (22.1%) were caused by lack of documentation of the relationships in PubMed abstracts. Miscellaneous reasons accounted for the remainder (20.6%).