Properties of two hydrolases: β-glucuronidase and N-acetyl-β-hexosaminidase were studied in lysosomal fractions of media-intima from arterial wall. These enzymatic activities change significantly with aging. In the arterial wall, the decrease in activities of β-glucuronidase and N-acetyl-β-hexosaminidase between young and old rats was highly significant while there was no notable change in the activities of acid phosphatase. These data are in agreement with the metabolic slow-down and the modifications of the gylcos-aminoglycan distribution in the media-intima of arterial wall with ag