A daily po injection of 5 mg of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) given to squirrel monkeys for a 2-wk period produces significant increases in liver weight, microsomal protein, cytochrome P-450 and the in vitro activity of various drug metabolizing enzymes. The results indicate that ascorbic acid deficiency may significantly impair both the induction of O-demethylase and the stimulation of the glucuronic acid system by DDT. The D-glucuronic/D-glucaric acid excretion ratio is significantly depressed within 2 days in monkeys fed the ascorbic acid deficient diet. In addition to ascorbic acid deficiency an unknown nutritional factor from the administration of a second lot of the ascorbic acid deficient diet also appears to cause an inhibition of the D-glucuronic/D-glucaric acid excretion ratio. This study provides evidence that interactions between nutritional status and toxic stress may significantly affect some routes of detoxification in the squirrel monkey.