A case regarding a newborn infant with severe Rh haemolytic disease, w
ho presented with the bronze baby syndrome and eventually died, is rep
orted. The postmortem examination showed marked extramedullary haemato
poiesis in the liver and spleen, heavy hepatic haemosiderosis and mild
intralobular cholestasis. The porphyrin content, which was assayed in
different tissues, was very high in the liver, suggesting that the in
creased erythropoiesis seen in Rh haemolytic disease leads to an incre
ased synthesis of porphyrins as by-products of haem synthesis. Phototh
erapy causes photodestruction, sensitized by bilirubin, of porphyrins
(mainly copper porphyrins), yielding brown photoproducts.