Clinical history, histopathological, ultrastructural and biochemical observations are presented in a juvenile MLD with onset at 8 years and death at 20 years. The findings are compared with related ones in different age groups, and current views on sulfatide metabolism and enzymatic pathogenesis in MLD are briefly entertained. It is postulated that the relatively well established morphological and chemical stability of the nervous tissue at the time of appearance of the metabolic derangement was an important factor in the pathomechanism of the disease process in this particular variant.