A chemical method for the selective estimation of myo-inositol coexisting with an excess sugar was described. To adopt the periodate oxidation method, an excess sugar (10-1000 : 1 W/W), should be removed by filtration through a Dowex 1×1 (OH^- ) bed, after the complete oxidation of the sugars to the acidic compounds by heating with 0.08 equivalent of barium hydroxide for 10 minutes at 100℃. Then, the amount of myo-inositol in the filtrate was estimated by the periodate oxidation technique. From the above experiments, it was found that 5-50mg % of myo-inositol added to the 5 per cent sugar solution could be determined spectrophotometrically with high reproducibility, within an experimental error of ±3 per cent. As an alternative method, the acetylation of myo-inositol and the determination of resulting six ester bonds according to the usual hydroxamate method was proposed.