Sodium, potassium and water absorption was studied over the whole length of rat jejunum and ileum by an in vivo marker perfusion technique. The composition of solutions were similar to the oral rehydration solution currently in use for the treatment of acute diarrhoeal diseases. The study shows that bicarbonate and chloride containing glucose or glycine electrolyte solutions induce a significantly greater absorption of sodium, potassium and water compared to those containing chloride only. The study also confirms that an amino acid such as glycine is as efficient as glucose in promoting the absorption of sodium, potassium and water from rat small intestine.