1. The ferritin content of liver and spleen in normal and iron-loaded rats decreased during repeated phlebotomy. 2. During increased iron demand, ferritin is degraded in toto. 3. With the ESI and EELS technique the iron distribution was followed in different cell types and cellular compartments. 4. We have demonstrated two methods of iron mobilisation: (a) catabolism of lysosomal ferritin in toto and (b) delivery of ferritin from parenchymal cell into the bile and degradation of ferritin in toto.