Peripheral T lymphocytes of renal allograft recipients were phenotyped for their expression of the CD3-T cell receptor (TCR) complex. The majority of T cells from patients with stable graft function had normal CD3 but diminished TCR alpha/beta heterodimer expression, while TCR gamma/delta + T cells were increased in some cases. Acute rejection was associated with an increase in TCR alpha/beta + T cells to normal levels.