The objective of this study was to elucidate an association between Apo- E4 allele and CSF biomarkers Aβ42 and tau for the diagnosis of Alzheimers Disease (AD) patients. Aβ42 and tau protein concentrations in CSF were measured by using ELISA assays. The levels of Aβ42 were found to be decreased where as tau levels increased in AD patients. Moreover in AD patients Apo-E4 allele carriers have shown low Aβ42 levels (328.86 ± 99.0 pg/ml) compared to Apo- E4 allele non-carriers (367.52 ± 57.37 pg/ml), while tau levels were higher in Apo-E4 allele carriers (511 ± 44.67 pg/ml) compared to Apo-E4 allele non-carriers (503.75 ± 41.08 pg/ml). Combination of Aβ42 and tau resulted in sensitivity of 75.38% and specificity of 94.82% and diagnostic accuracy of 84.30% for AD compared with the controls. Therefore low Aβ42 and elevated tau concentrations in CSF may prove to be a better diagnostic marker for AD along with the Apo-E4 allele.