Post-mortem tissue was obtained from subjects with Parkinson's disease (PD), Alzheimer's disease (AD) and age-matched controls. Iron levels were measured from various sites of the basal ganglia and neocortex using atomic absorption spectrophotometry. The results indicate that iron levels are increased in the substantia nigra and the lateral segment of the globus pallidus of parkinsonian tissue. In contrast, the medial segment of the globus pallidus shows reduced iron levels in AD when compared to age-matched controls. No significant alterations of iron concentration were detected in AD in any region. These results are discussed in terms of the role of iron in the basal ganglia, mechanisms of abnormal deposition and possible neurotoxicity in PD.