The fate of smooth form lipopolysaccharide (LPS) from Salmonella abortus-equi injected intravenously in rats was studied. In the circulation, the LPS formed a stabile complex with high density plasma lipoprotein and was cleared from the blood primarily into the liver at a slow rate (over a period of two days). In the liver, LPS was first detectable in Kupffer's cells and granulocytes; from there it was later redistributed (after two days) into hepatocytes. While it was in the circulation, no evidence for alteration in the chemical structure of the LPS was found. However, partial loss of fatty acids occurred in the liver and also other organs such as the spleen. The excretion of chemically altered LPS continued for several weeks, mainly via the feces and, to a small extent, in the urine.