The oligosaccharidoses are a group of metabolic disorders resulting from a deficiency in enzymes responsible for the catabolism of protein bound oligosaccharides and are typified by the accumulation of corresponding sugars in the urine. Screening is typically accomplished using thin layer chromatography. However, analyte specificity can be a problem and thus complicate interpretation of results. For this reason we developed a mixed mode liquid chromatography tandem mass spectrometry assay for the screening of the oligosaccharidoses which potentially mitigates many of the problems associated with thin layer chromatography. Samples from patients previously diagnosed with I-Cell disease, mannosidosis, Pompe, galactosialidosis, and fucosidosis were derivatized with 3-methyl-1-phenyl-2-pyrazolin-5-one and subjected to analysis by liquid chromatography tandem mass spectrometry. Results were compared to normal control samples. Preliminary results suggest that each oligosaccharidoses produces a unique selected reaction monitoring fingerprint and that the developed method may be an effective screening and diagnostic tool for these disorders.