The surface antigen profile of 8 sublines of K-562 cells, the original line, and the clone RA6 was determined with a panel of 12 monoclonal antibodies reactive with hematopoietic cell differentiation antigens. Cells from all sublines expressed the precursor hematopoietic antigen reactive with RFB-1, the T-cell antigen reactive with OKT17, the B cell/granulocyte antigen reactive with BA-1, the My-1 antigen, and glycophorin A which reacted with R10. A low percentage of cells in some of the sublines expressed platelet/monocyte glycoprotein I binding AN51, monocyte antigen binding 63D3, and an erythroblast/monocyte/platelet antigen binding 5F1. The use of a panel of K-562 sublines demonstrates that K-562 cells do share several "common" antigens but express a marked diversity and variability of other hematopoietic antigens.