Chronic inflammation associated with the amyloid plaques may represent an acute phase response in the brain. We quantitated the levels of two inflammatory markers; alpha 1-antichymotrypsin (alpha 1-ACT) and interleukin 1 beta (IL-1 beta) in paired serum and cerebrospinal fluid (CSF) samples from 40 patients with Alzheimer's disease (AD), 20 patients with Parkinson's disease (PD), and 42 age-matched controls. No differences in serum or CSF levels of either alpha 1-ACT or IL-1 beta were found between the groups. However, some AD patients had increased alpha 1-ACT index, suggesting an intrathecal production of alpha 1-ACT. Although alpha 1-ACT or IL-1 beta might be involved in the pathogenesis of AD, our results show that their measurement in serum or CSF is not valuable to support the clinical diagnosis of AD.