Mannitol, a non-absorbent compound may suppress free drinking in rats. It was suggested that the osmotic accumulation of water in the intestine produced a satiety signal by distending the wall of the gut, which resulted in the reduction of intake. However, we never obtained this suppression during the first exposure to mannitol in water deprived rats, while subsequent administration of this compound significantly reduced the amount of the consumed fluid. Moreover, mannitol preloaded intragastrically increased and not decreased fluid intake. Results show that in water-deprived rats the accumulation of the fluid in the intestine did not result in satiety. The subsequent reduction of the fluid intake might be associated with the development of a taste aversion in the rats.