The immunoglobulin-related, T-cell specific gamma gene is rearranged in a wide variety of murine T lymphocytes. We detected gamma-gene transcripts in all cloned cytotoxic T lymphocytes examined but in only 1 of 11 T-helper cell lines or hybridomas. Although in cytotoxic T cells, the rearranged gamma gene seems to have been assembled from the same germ-line variable and joining gene segments, the transcribed gene exhibited distinct sequence diversity near the junction between these segments.