The cerebrospinal fluid levels of amyloid beta 1-42 (Aβ1-42), total tau and tau phosphorylated at threonine 181 (ptau181) are well established biomarkers of cerebral amyloid pathology and tau related neurodegeneration, two hallmarks of Alzheimer's disease. These biomarkers can help to improve diagnostic accuracy and consequent decisions on counseling, support, and therapy of patients with mild cognitive impairment and dementia. The use of biomarkers is part of the proposed new criteria of AD diagnosis. It may be particularly helpful in cases of atypical clinical presentation and uncertain diagnosis, and if an important benefit for the patient is expected. The ongoing development of new biomarkers based on less or non-invasive procedures will allow for a larger use of biomarkers to improve the diagnosis of cognitive impairment.