The developmental regulation of antigen receptor gene transcription and recombination are mediated by cis regulatory elements. At the T cell receptor beta chain locus (TCRbeta), two DNase I hypersensitive sites within the Jbeta2-Cbeta2 intron contained binding sites for NF-kappaB and additional nuclear factors and were postulated to be involved in controlling TCRbeta transcription and V(D)J recombination. To test this possibility, we deleted these elements from the mouse genome by homologous recombination and assayed the effect on transcription of both the germline and rearranged TCRbeta locus, and on TCRbeta rearrangement in T and B lymphocytes. We found that TCRbeta transcription and V(D)J recombination and T cell development were normal in these mutant mice. Therefore, the Jbeta2-Cbeta2 intronic elements are dispensable for TCRbeta assembly and function.