<b>Computational prediction of damage associated non synonymous SNPs of CYP17A1 and CYP19A1 gene</b> The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. CYP17A1 and CYP19A1 are the key proteins involved in steroidogenesis. Majority of polymorphisms have yet not been evaluated for their possible damaging effects on protein structure and function of both the genes. In present analysis, we tried to find out the effect of damage associated nsSNPs of both CYP17A1 and CYP19A1 gene by using various computational algorithms. Out of 205 and 246 nsSNPs reported for CYP17A1 and CYP19A1 gene, total 13 and 7 were predicted to affect the structure and function respectively. R125Q, R416H and F453S substitutions of CYP17A1 gene were not reported previously hence provide the new dataset of unexplored SNPs for their validation. By our results we also found that substitution of mainly Arginine or Phenyl alanine within conserved domain of redox binding, heam binging and redox partner site would cause partial or complete loss of function of both CYP17 and CYP19 gene. CYP450, Steroidogenesis, Aromatase, SNP, Oestrogen, Testosterone 635-646 Issue-6 Volume-1 Richa Bhatnager | Ranjeet Kaur | Amita Suneja Dang | Twinkle Dahiya