A central role of iron in the pathogenesis of Parkinson's disease (PD) has been discussed for many years. Numerous studies using magnetic resonance imaging and transcranial sonography have been performed to detect alterations in tissue iron content of the substantia nigra. This manuscript reviews the findings of this still controversial issue and indicates that specific abnormalities that are suggested to be related to a disturbance of iron homeostasis may play an early role in the pathogenesis of PD.