Granulocytes from patients with chronic myelogenous leukaemia (CML) have been previously shown to have aberrant sialylation of membrane glycoproteins. We have examined the granulocytes from CML patients receiving intermittent chemotherapy to determine the relationship of the oligosaccharide changes to treatment. Compared to cells from non-leukaemic patients, granulocytes from untreated CML patients showed less adherence to nylon wool, decreased reactivity with peanut lectin, and decreased binding of the synthetic chemotactic peptide formyl-methionine-leucine-phenylalanine (FMLP). Granulocytes from CML patients treated with chemotherapy showed nylon wool adherence, peanut lectin reactivity and FMLP binding comparable to non-leukaemic cells. Chemotherapeutic agents may interfere with oligosaccharide synthesis with a resulting change in the composition of cell surface glycoconjugates.