In previous studies it was found that the chemical changes in the blood of splenectomized rats suffering from Bartonella muris anemia consist of an increase in the total fats and fatty acids, a drop in lecithin and total cholesterol, a rise in blood chloride concentration, a moderate acidosis, and a variable drop in blood sugar. The liver glycogen is almost depleted. These changes are attributable either to the severity of the anemia or to the infection. Blood chemistry studies on splenectomized rats that were not carriers of Bartonella muris and in which no infection or anemia occurred revealed no significant deviation from the normal. Splenectomy in the rat free from Bartonella rauris infection has no effect on metabolism that is demonstrable in the usual chemical analyses of the blood.The present studies were undertaken in order to determine the effect of splenectomy on the metabolism of copper and iron in the rat free from latent Bartonella muris infection.