The effects of furosemide and pentobarbital on the edema associated with cryogenically-induced cerebral lesions in the rhesus monkey were quantitatively measured. Both drugs caused a decrease in the increments of water, sodium, and chloride in the damaged hemisphere. In addition, the pentobarbital was associated with a decrease in the uptake of serum protein. The effects of the two drugs were not additive. It is proposed that furosemide be given a clinical trial in the treatment of human cerebral edema.