Accumulating evidence implicates a role for altered metal homeostasis in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). However, few investigations have addressed this issue in dementia with Lewy bodies (DLB). The aim of the present study was to investigate metal concentrations in cerebrospinal fluid (CSF) and plasma from patients with DLB and other neurodegenerative disorders. To that end, CSF and plasma samples were collected from 29 patients with DLB, 174 patients with AD, 90 patients with AD with minor vascular components, and 51 healthy volunteers. Total concentrations of Mg, Ca, Mn, Fe, Cu, Zn, Rb, Sr, and Cs were determined using mass spectrometry. Patients with DLB had elevated Ca and Mg levels in CSF and Mg levels in plasma as compared to all other groups (p<0.001). Furthermore, a combination of CSF-Mg and CSF-Ca could distinguish DLB from AD with a sensitivity of 93% and a specificity of 85%. Cu levels in both CSF and plasma tended to be higher in DLB compared to the other groups, but these trends failed to reach significance after correction for multiple comparisons. Mn, Fe, Zn, Rb, and Sr concentration in CSF or plasma were similar in all groups. The observed elevations of CSF-Mg, CSF-Ca and CSF-Cu may contribute to or be associated with the neurodegenerative process in DLB. Furthermore, determination of CSF-Mg and CSF-Ca concentration may be a valuable tool in distinguishing DLB from AD.