Late infantile metachromatic leukodystrophy (MLD) was successfully diagnosed in utero by demonstrating the absence of arylsulfatase-A in amniotic fluid using diethylaminoethyl-Sepharose column chromatography. Diagnosis by amniotic fluid using an ion-exchange column is more rapid and reproducible as compared with those reported previously. The diagnosis was confirmed by the absence of arylsulfatase-A in fetal brain, liver, and kidney tissues as well as by the marked accumulation of sulfatide in kidney. The kidney is the most appropriate organ for the demonstration of sulfatide accumulation in fetal tissues in MLD.