1. Lysosomal stability was slightly increased in regenerating livers from rats receiving a zinc-deficient (< 0.5 mg/kg) diet for 10 d before surgery.
2. The activity of superoxide dismutase (EC 1.15.1.1) was significantly reduced in the same tissues.
3. The results do not support the view that increased lysosomal fragility represents a major biochemical consequence of nutritional Zn deficiency in animals.