1. A vacuum skin-blistering technique has been successfully applied and the human epidermal tissue so obtained has been examined for glycogen content and some of the enzymes involved in glycogen metabolism.
2. Normal values for glycogen phosphorylase, acid α-glucosidase and amylo-1,6-glucosidase (debranching enzyme) in epidermis are reported. Glucose 6-phosphatase activity was not detected.
3. Examination of two patients with Type II glycogen storage disease (Pompe's Disease—lack of lysosomal acid α-glucosidase) revealed an absence of the acid α-glucosidase in their skin.
4. The enzymic lesion in Type V glycogen storage disease (McArdle's Disease—lack of muscle phosphorylase) was not reflected in the epidermal tissue of a patient and a normal level of the enzyme was observed.