In this observational, case-control study in infertile women, we observed elevated serum oxidative stress that was significantly correlated with an increase in serum paraoxonase-1 activity and without any evidence of a proinflammatory reaction. These results suggest a protective role of paraoxonase-1 against inflammation in this clinical setting. (Fertil Steril (R) 2010;94:1132-4. (C)2010 by American Society for Reproductive Medicine.)