The TATA box-binding protein (TBP) is a key transcription factor required for transcription by all three eukaryotic RNA polymerases. It consists of a conserved carboxy-terminal DNA binding domain and a highly divergent amino terminal domain. TBP and different sets of TBP-associated factors (TAFs) constitute at least four multisubunit complexes referred to as SL1, TFIID, TFIIIB, and SNAP(C). SL1, TFIID, and TFIIIB are required for transcription by RNA polymerases I, II, and III, respectively, while the SNAP complex is involved in transcription of the small nuclear RNA (snRNA) genes by RNA polymerases II and III. TBP also associates with a number of basal transcription factors such as TFIIA and TFIIB, and with several regulatory factors such as VP16, E1A, and p53. Here we describe the characterization of a panel of monoclonal antibodies (MAbs) directed against the amino-terminal domain of human TBP. These MAbs recognize different TBP epitopes, some of which have been precisely defined. Different MAbs recognize different TBP- containing complexes and several of them crossreact with TBP from other species. These antibodies can be used to purify TBP-containing complexes in a functional form and should be useful to identify new protein-protein interactions involving TBP.