Capillary zone electrophoresis with indirect UV detection at 215nm was applied for the separation and determination of mannitol (MA), sorbitol (SO) and xylitol in the form of anionic borate–polyol complexes. The separation was carried out in a fused silica capillary (total length 60cm, effective length 50cm, I.D. 50μm) at 25kV. The optimized background electrolyte was 200mM borate buffer (pH 9.3, adjusted with triethylamine) containing 10mM 3-nitrobenzoate as the chromogenic co-ion. The separation took ∼13min. The rectilinear calibration range was 0.2–2mgmL−1 for MA and SO when using xylitol (1mgmL−1) as the internal standard. The limit of detection at a S/N of 3 was ∼30μgmL−1 for either analyte. The method was used for the assay of MA or SO in pharmaceutical infusion solutions. The RSD values were 0.15% or 1.07% (n=6) when determining 100mgmL−1 of MA or 50mgmL−1 of SO in commercial infusion solutions. The results were in good agreement with those of pharmacopoeial iodimetric titration.