The T-cell receptor (TCR)/CD3 complex is the surface molecule responsible for the highly specific response to foreign antigens, including tumour-associated antigens. and correlations have been observed with disease status. Recently, low amounts of CD3 gamma and CD3 zeta chains in the CD3/TCR complex have been reported in long-term tumour-bearing mice as a possible mechanism for the impaired T-cell responses. In this study we report a B-cell lymphoma in which T-cell CD3 zeta expression correlated with disease activity.