Our work on isolated rat intestine aimed at studying the hypothesis that the intestinal transport of manganese was carrier-mediated and, consequently, subjected to saturation. Our results confirm this hypothesis, assessing the concentration of carrier saturation for manganese at 0.5 mM. As this concentration, which may determine self-limitation in the intestinal absorption of this metal, is much higher than the maximal allowed concentration of the EEC Standard (50 mg/l), food and water should be carefully monitored for their manganese content in order to avoid reaching toxic concentrations in blood and tissues.