Rhesus monkeys were intoxicated with methyl alcohol, using an initial dose of 2 gm/kg and subsequent doses were administered in order to maintain an attenuated and prolonged state of intoxication. Arterial blood samples were drawn for methyl alcohol, formate, PO2, PCO2, and pH, which were monitored periodically throughout the course of the experiment. With the use of these procedures monkeys developed metabolic acidosis with the accumulation of formic acid in the blood and a corresponding decrease in blood bicarbonate. These animals served as models, which allowed for ocular evaluation for early signs related to methyl alcohol poisoning. A mechanism to explain toxicity is proposed and discussed.