To assess whether serum copper in Alzheimer disease (AD) correlates with cognitive scores, beta-amyloid, and other CSF markers of neurodegeneration. The authors studied copper, ceruloplasmin, total peroxide, and antioxidants levels (TRAP) in serum; beta-amyloid in plasma; and copper, beta-amyloid, h-tau, and P-tau in the CSF of 28 patients with AD and 25 healthy controls, in relation to clinical status. Serum copper (p < 0.0001), peroxides (p = 0.002), a copper fraction unexplained by ceruloplasmin (p < 0.0001), and CSF h-tau (p = 0.001) were increased in AD, whereas serum TRAP (p = 0.03) and CSF beta-amyloid were decreased (p < 0.0001). Plasma beta-amyloid increased with age in healthy controls (r = 0.6; p = 0.05). CSF markers of AD correlated with serum copper variables. CSF copper was partially dependent on the serum copper fraction unexplained by ceruloplasmin (t = 2.2, p = 0.04). CSF beta-amyloid seemed to be related to serum copper (r = -0.46; p = 0.002). Mini-Mental Status Examination scores correlated positively with beta-amyloid (r = 0.46, p = 0.002) and inversely with copper unexplained by ceruloplasmin (r = -0.45, p = 0.003). The authors' results confirm the existence of changes in copper component distribution, particularly the copper fraction unexplained by ceruloplasmin and support the hypothesis of a beta-amyloid and copper connection in Alzheimer disease.