Most B-cell chronic lymphocytic leukemias and a small normal subset of B lymphocytes express the T-cell-associated CD5 antigen; expression of other T-cell antigens has been reported only rarely. The authors report two cases of typical B-cell chronic lymphocytic leukemia, seen during 1 year, in which two-color flow cytometric analysis documented expression of the T-cell-associated CD8 antigen by the monoclonal B cells. Genotypic studies showing immunoglobulin but not T-cell-receptor gene rearrangements confirmed the B-cell origin of the neoplastic cells. The true frequency of the CD8-positive B-cell chronic lymphocytic leukemia, any clinical implications, and the possibility of a normal subset of CD5-positive CD8-positive B cells remain to be determined.