Approximately 67% of peripheral blood lymphocytes in a case of nonmycosis fungoides‐type cutaneous T‐cell lymphoma, exhibited Sézary‐like changes. Immunotyping showed a helper phenotype with an abnormally faint expression of the T3 membrane antigen, while quantitative electron microscopic study was suggestive of neoplasia. However, T‐cell receptor gene study did not show any DNA rearrangement in Ficoll‐separated blood lymphocytes, whereas clonal T‐cell proliferation was simultaneously evidenced in cutaneous (non‐Sézary‐like) tumor cells. It is concluded that reactive nonneoplastic Sézary‐like cells may be present not only in various benign conditions, as previously known, but also in T‐cell lymphomas. This study provides further evidence for the nonspecificity of Sézary‐like changes, and stresses the utility of T‐cell receptor gene rearrangement study for diagnostic and prognostic procedures during the course of T‐cell lymphoproliferative disorders.