The repertoire of TCR V beta genes transcribed and expressed within the central nervous system was determined in mice with experimental allergic encephalomyelitis. Disease was induced in (PL/J x SJL/)F1 mice by immunizing with myelin basic protein-acetylated peptide 1-11, and mice were sacrificed at intervals from day 3 postimmunization to 3 wk after recovery from disease. Transcription of V beta genes was determined by reverse transcriptase polymerase chain reaction on RNA extracted from spinal cord, and expression of the V beta gene products was detected by immunohistochemistry with mAb specific for various V beta proteins. Multiple V beta genes were found to be transcribed and expressed in the central nervous system starting 7 days after immunization, and continuing up to 3 wk after clinical recovery. Preferential utilization of a single TCR V beta gene was not detected in the central nervous system at any time in the course of disease.