Transferrin is one of the key proteins of iron metabolism in mammalians. It is responsible for the transfer of the essential iron(III) ions through the biological fluids from absorption to storage and utilization sites. Moreover, transferrin is involved in the metabolism of other metal ions that are either trace or toxic elements. In recent years the crystal structure of transferrin has been solved at high resolution. This has allowed an extensive reinterpretation of the many spectroscopic studies carried out on this protein in the last decade as well as the elucidation of some interesting structure-function relationships. We review here recent progresses in transferrin biochemistry, particular focus being given to those aspects that are relevant from a medical point of view.