A direct dye-binding technique has been developed to measure total glycosaminoglycans in urine. Fifty or 100 microliters of urine was mixed with a solution of Azure A (10 mg/l) and Azure B (10 mg/l) and the resulting decrease in absorbance at 610 nm was measured. The standard curve with chondroitin sulfate C was linear from 1 to 20 micrograms/assay. The normal value for total urinary glycosaminoglycans in adults was 1.8 +/- 0.6 g/mol creatinine. Other normal values were age-dependent. The assay is inexpensive, simple, precise, sensitive and suitable for screening for the mucopolysaccharidoses in pediatric patients.