Over the past decade, a tremendous amount of consistent data have accumulated showing reduced levels of the 42 amino acid isoform of amyloid-beta (Abeta(42)) in cerebrospinal fluid (CSF) from patients with mature as well as incipient Alzheimer's disease (AD). However, as CSF analyses necessitate a spinal tap, which some consider hard to implement in the clinical routine and in clinical trials, there is a strong interest in the possible association of Abeta levels in plasma with AD. This review provides an update on the current status of research on plasma Abeta as a biomarker for AD in the context of recent patents in the field.