As the spectrum of therapeutic options broadens, the possibility of an early and accurate diagnosis of Alzheimer's disease (AD), or even isolation of a group at high risk of subsequent cognitive decline, is focusing widespread attention. Therefore, biological markers or risk factors of AD are highly desirable. In this work, we give an overview of the most extensively studied AD biomarkers, namely beta-amyloid, tau protein, and phosphorylated tau-protein, alone or in combination. Moreover, we describe the role of inflammatory markers (cytokines, acute phase proteins), oxidative stress markers (isoprostanes, 8-hydroxyguanine, 3-nitrotyrosine, plasma antioxidants, redox transition metals), homocysteine and related vitamins, cholesterol and 24S-hydroxycholesterol in the diagnostic process or prediction of AD. We briefly review less popular, though promising markers of AD - markers of apoptosis, neuronal thread protein, acetyl- and butyrylcholinesterase, sulfatide, kallikreins, matrix-degrading metalloproteinases, and novel isoforms of beta-amyloid and tau. Finally, we discuss the clinical applicability of AD-related biological markers.