Iron (Fe) and aluminum (Al) eliminations in bile were studied in rats after intravenous administration of Fe, Al, deferoxamine mesylate (Desferal, Ciba) (DFA), feroxamine (FeA), and aluminoxamine (AlA) at the dose of 50 mumole/kg body weight. Bile was obtained from the bile duct of anesthetized rats, and the concentrations of Fe and Al in bile were measured by an inductively coupled plasma optical emission spectrometer. The results showed an increase of Fe elimination in bile, from 10 to more than 20 mumole/liter after Fe and also after Al administration; an increase to about 350 mumole/liter after DFA administration; to 250 mumole/liter after FeA administration; and to 100 mumole/liter after AlA administration. Aluminum elimination in bile was increased only after Al and particularly after AlA administration but not after Fe and FeA administration. In conclusion, Al and AlA were able to increase Fe elimination in bile. Thus Al overload observed in hemodialyzed patients may induce an excessive iron loss in bile and partly explain microcytic anemia.