Flavobacterium meningosepticum peptide: N-glycosidase-mediated deglycosylation of N-linked glycan strands of glycoproteins has been found to be strongly influenced by the ionic strength of the assay medium. By use of a modification of a previously published assay procedure for quantitative analysis of glycan release we have been able to improve reproducibility and thus to compare the extent of deglycosylation achieved under a variety of conditions of ionic strength. We have observed that enzyme activity is adversely affected by high ionic strength buffers such as those recommended for deglycosylation of various glycoproteins and recommend the use of low ionic strength buffers for routine use.