Background/Aim. Introduction of acetylcholine esterase inhibitors as a symptomatic treatment of Alzheimer's disease (AD) has additionally highlighted the importance of diagnostic markers in cerebrospinal fluid (CSF) for early AD diagnosis: low level of 42 amino acid form of amyloid-β peptide (Aβ42), and levels of tau protein (T-tau) and phosphorylated tau protein (P-tau). The aim of this study was to diagnostic potential of CSF biomarkers T-tau, P-tau and Aβ42 as biochemical markers for AD. Methods. Lumbar puncture was performed in 63 patients with AD and 26 control subjects who passed orthopedic surgery. The Innotest, ELISA sandwich test (Innogenetics - Belgium) was used for measuring the levels of T-tau, P-tau and Aβ42. Results. The patients and the control group did not differ in age, education and sex. Mean levels of CSF T-tau and P-tau were significantly higher in the patients with AD (p < 0.001) compared to the control group, in contrast to significantely lower CSF Aβ42 in AD group (p < 0.001). A significant progressive decrease of Aβ42, as well as significant progressive increase of T-tau and P-tau was found among AD subgroups (according to MMSE staging) and controls. Conclusion. The obtained results suggest that these biomarkers may be supportive in the diagnosis of AD, especially in the early course of the disease and could be used in the routine clinical practice considering the approaching target therapeutics.