We studied neutrophil chemotaxis and surface membrane glycoproteins in 12 patients suffering from myeloid disorders with abnormal karyotype using in vitro techniques in all 12. Chromosome studies were also carried out virtually simultaneously. We chose to study only patients showing a deficit of chemotaxis (p < 0.001). Ten of these patients revealed a clonal chromosome abnormality in most of the leukemic cells. The monoclonal antibody technique using MoAb 60.1, 60.3, 60.5, OKM1, LFA-1 and 9E8 demonstrated normal leukocyte membrane glycoproteins CD 11a, b, c and CD 18 and therefore excludes that an abnormality of these is involved in the pathogenesis of altered leukocyte chemotaxis. No correlation between chemotactic deficit and any specific clonal chromosome abnormality was found.