The optimal composition for oral rehydration solutions remains controversial. Animal models have been used to assess the efficacy of new formulations but the relevance of these studies to the handling of oral rehydration solutions in human intestine during diarrhoeal disease states remains uncertain. Using steady state perfusion techniques we have compared water and solute transport from a variety of oral rehydration solutions in both the entire rat small intestine and in the human jejunum. Overall the pattern of water, sodium and glucose absorption was similar from the three oral rehydration solutions tested, indicating close parallelism between the two models despite the species and methodological differences. Although the relationship between the findings of these studies to the handling of oral rehydration solution in diarrhoeal disease states remains uncertain, we believe they do support the view that animal models may have a part to play in the preliminary screening of oral rehydration solutions before clinical trial.