The pH- and activator-dependence of toad plasma cathepsin activity assayed by hemoglobin digestion was characteristic of cathepsins B1 and D. 2. Dehydration, even to the point of death, did not produce a significant elevation of plasma cathepsin activity over controls. 3. Toads were remarkably resistant to the effects of splanchnic artery ligation, which also did not produce significantly higher plasma cathepsin levels. 4. Cardiac depression via the production of a myocardial depressant factor by cathepsins does not appear to be an important factor in dehydrational death in toads.