Several studies have investigated the possible involvement of viral agents,and among them herpes viruses,in the development of cutaneous T- cell lymphoma. The aim of our study was to determine whether T- cells specific to Epstein- Barr virus(EBV)- antigens were detectable among tumor- infiltrating lymphocytes infiltrating cutaneous lesions of a patient with Sé zary syndrome. To analyze responses to EBV, we used a transient SV- 40 origin- defective transformed simian cells transfection assay that permits an estimation of CD8 T- cell responses against a large number of HLA/viral protein combinations. This technique allowed the detection of EBV- specific T lymphocytes mainly directed against epitopes generated during the lytic cycle in the cutaneous lesions. This is, to our knowledge,the first descrip- tion of the presence of EBV- specific T lymphocytes among tumor- infiltrating lymphocytes infiltrating the lesional skin of a patient with Sé zary syndrome. Several studies have investigated the possible involvement of viral agents, and among them herpes viruses, in the development of cutaneous T-cell lymphoma. The aim of our study was to determine whether T- cells specific to Epstein-Barr virus (EBV) - antigens were detectable among tumor- infiltrating lymphocytes infiltrating cutaneous lesions of a patient with Sé zary syndrome. To analyze the responses to EBV, we used a transient SV-40 origin- defective transformed murine transfection assay that permits an estimation of CD8 T-cell responses against This technique allows the detection of EBV-specific T lymphocytes primarily directed against epitopes generated during the lytic cycle in the cutaneous lesions. This is, to our knowledge, the first descrip tion of the presence of EBV-specific T lymphocytes among tumor-infiltrating lymphocytes infiltrating the lesional skin of a patient with Sé zary syndrome.