Fifteen adult baboons were tranquilized with 1-(1-phenylcyclohexyl) piperidine hydrochloride (Sernylan) early in the morning and changes in hormonal levels and energy substrates were determined as the animal awoke. Serum-free fatty acids and plasma cortisol rose during the 4-hr observation period. This was accompanied by a similar rise in urinary catecholamines and 11-hydroxycorticosteroids. An elevation in serum glucose and a decrease in serum insulin were observed but these changes did not achieve statistical significance. Serum growth hormone decreased during the experimental period. These changes are discussed in relation to the use of the awake baboon for experimental shock studies.