Aim: Hyperbilirubinemia causes oxidative stress. Method: We evaluated three oxidative stress markers in hyperbilirubinemic neonates (native/total thiol levels, serum ferroxidase activity and ischemia modified albumin (IMA), comparing these levels to levels in a control group to determine which indicators were the most sensitive.Results: Serum from 124 term infants (67 with pathologic jaundice and 57 controls) were evaluated. Native/total thiol ratio was significantly lower (p:0.021) while disulfide levels were significantly higher (p:0.001) in the jaundiced group. There was no significant difference in ferroxidase (p:0.603) or IMA (p:0.251) levels.Conclusion: Altered thiol/disulfide homeostasis in the favor of disulfide indicates augmented oxidative stress in jaundiced term infants. The lack of alteration in ferroxidase or IMA levels suggests these latter alterations take more time or more severe oxidative stress to become altered or are not as sensitive as the thiol/disulfide ratio to detect oxidative stress states.