Down syndrome (DS) is associated with oxidative stress which occurs due to over expression of Superoxide dismutase-1 (SOD-1) gene, located in chromosome 21q 22.1. This results in increased free radical generation causing damage to cellular components. The aim of the study is to quantify the Cytokinesis block Micronucleus score (CBMN) and Total antioxidant status (TAS) in DS and establish a relationship between both. Our results suggest that CBMN frequency (3Vs1) and TAS levels (357.97 Vs 516.3 uM/L) were significantly increased and decreased respectively compared to matched controls. A significant negative correlation was observed between the CBMN score and TAS level. Hence, we conclude that CBMN score can be considered as a biomarker of genotoxicity in cases with trisomy 21.