The present study is an attempt to correlate cell-surface saccharide composition and/or disposition with malignant behavior and differentiation of two established human neuroblastoma sublines. The methodology applied was quantitative flow-cytometric evaluation of binding data for sugar-specific lectins in conjunction with cell-surface modification by specific glycosidases. The relevant parameters were both the number of binding sites and their apparent affinity constants for the respective lectins on native cells as well as the expected shift of those values after sequential treatment with specific glycosidases. The main conclusions from the findings may be summarized as follows: 1. There appears to exist a correlation between differentiation and/or maturation of neural cells and their cell-surface oligosaccharide patterns, as deduced indirectly by the biophysical approach of quantitative evaluation of lectin-binding data. More specifically, our findings support the hypothesis of a strong correlation between the degree of sialylation of terminal saccharide structures and the relative immaturity and/or lack of differentiation of the respective cells by morphological and biochemical criteria. 2. The combined application of specific lectins and glycosidases should be further exploited for similar purposes since it yields unequivocal information, provided that all biochemical and biophysical methods are scrutinized for their specificity. 3. Flow cytometry with fluorescence-labeled lectins is especially suited for the purposes mentioned since it allows quantitative binding studies to be conducted in a quick and uncomplicated manner. Most importantly, these data can be derived from intact living cells.