Research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer's disease (AD), which has been translated into an ongoing development of disease-modifying treatments. These new drug candidates are targeted on inhibiting amyloid-beta (Abeta) production and aggregation or tau aggregation. If these drugs prove to be efficient, diagnostic tools enabling early diagnosis of AD will be of great value. Also in drug development, it is important to co-develop biomarkers to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). The core candidate CSF biomarkers Abeta42, total tau (T-tau), and phosphorylated tau (P-tau) have been shown to have a high diagnostic performance to identify AD also in the early phase of the disease. This paper reviews recent research advances on these CSF biomarkers for use in clinical diagnosis and in clinical trials in AD.