This chapter discusses pathophysiology of jaundice, which is characterised by yellowish discoloration of the skin and sclera due to the deposition of yellowish pigment, bilirubin. Bilirubin is a normal product of erythrocyte breakdown. The death of red cells is essentially a phenomenon of aging. When a red cell has lived its normal lifespan, it loses its vitality and is trapped by the macrophages of the reticuloendothelial system, now generally called the macrophage phagocytic system (MPS). Macropahges phagocytose the red cells or their fragments, release the haemoglobin and break it into its components. Macrophages split haemoglobin into haeme and globin. The haeme oxygenase reaction is followed by reduction of biliverdin to bilirubin by the enzyme biliverdin reductase. The product of conjugation, bilirubin glucuronide, is excreted by the hepatocytes through the biliary canaliculi. The decline in haemoglobin is more due to inadequate erythropoiesis rather than due to haemolysis.