Chemical compounds foreign to mammalian liver stimulate the hepatic microsomal system to increased, but nonspecific, enzymatic activity. The stimulatory effect on liver enzymes being non-specific, increased hepatic activity results also in an accelerated metabolism of normal body constituents and a more rapid rate of utilization of administered drugs. One substance, nitrilotriacetic acid, an effective chelating agent used as a partial substitute for phosphate in detergents, has not been thoroughly tested for metabolic effects on mammalian microsomal systems. Should undegraded NTA be discharged into the environment in sizable amounts and concentrate in potable water supplies, cumulative exposures of man to the chemical could result in chronic illness or debilitating physiological states. In an attempt to evaluate the metabolic effects of this foreign substance on mammalian systems, the authors have studied several enzymes in the liver and intestine of mice subjected to chronic oral administration of the sodium salt of nitrilotriacetic acid in drinking water at a concentration ten times the expected environmental level.