A specific microdetermination of d-glucosamine in the presence of other hexosamines is presented. This method is based on the specificity of yeast hexokinase for d-glucosamine and of yeast acetylating enzyme for d-glucosamine 6-phosphate. When coupled with a method for determination of total hexosamine, the amount of another hexosamine also present (such as galactosamine) can be calculated by difference.