The acute effects of cholera exotoxin on selected absorptive and secretory functions of the small intestine of the dog were studied before and during fluid production induced by cholera exotoxin. To minimize systemic fluid and electrolyte depletions and to permit serial observations, short Thirty-Vella loops of either jejunum or ileum were employed. The unidirectional sodium flux from lumen to blood was unchanged during exotoxin-induced fluid production. Sodium flux from blood to lumen, however, was markedly increased. Glucose absorption was unaltered. These observations in the dog indicate a preservation of the lumen to plasma flux of sodium and the absorption of glucose with an increased plasma to lumen flux of sodium associated with secretion of water and other electrolytes during cholera exotoxin fluid production. It is suggested that one of the principal actions of cholera exotoxin is to stimulate the movement of fluid and electrolytes into the intestinal lumen.