5 mg of lipopolysaccharide derived from E. coli which was dissolved into 1 ml of water was injected through the femoral vein. 2 hours after the injection of endotoxin, horseradish peroxidase (HRP) was injected through the femoral vein. 2 minutes after the injection of HRP both cochleas were infused with a fixing solution of 2% glutaraldehyde through the previously opened bullas. 5 minutes after infusion of the fixative, guinea pig was decapitated. Ultrathin cross sections of each turn of cochlea were taken at several locations and observed through an electron microscope. Blood sludging was observed in many strial capillaries in upper turns. In third and forth turns, HRP reaction product was not observed in 10% of the strial capillaries, which meant the strial blood flow was completely blocked.