Thiols constitute the largest part of the antioxidant system with the ability to protect cells and tissues from oxidative stress (OS). Studies report that glutathione (GSH) depletion may lead to the induction of SO and several negative effects due to the impairment of the thiol/disulfide balance. The aim of the study was to determine changes in thiol/disulfide balance in children with chronic kidney disease (CKD). A prospective study was conducted on a group of 71 children with CKD and a control group of 71 healthy subjects. Thiol/disulphide homeostasis (total thiol, native thiol, reduced thiol, oxidised thiol and disulphide levels) was measured using spectrophotometric method and the results were statistically analysed. In patients with CKD, a significant reduction in total, reduced and oxidized thiol levels was recorded 498,472 ± 99,192 µM/L vs 424,405 ± 34,012 µM/L p < 0.005; 292,202 ± 52,059 µM/L vs 338,152 ± 93,333 µM/L p < 0.005; 132,202 ± 70,742 µM/L vs 160,326 ± 49,993 µM/L p < 0.005. Protein-bound thiol groups (SH) showed an increasing trend in the control group (3,348 ± 1,739 vs 5,652 ± 1,958 µM/L p < 0.005); while total and free SH groups were higher in patients with CKD (138,018 ± 30.28 vs 103,941 ± 12,424 µM/L p < 0.005; 91,575 ± 14,385 vs 87,342 ± 11,048 µM/L p < 0.005). The study demonstrates the persistence of a pro-oxidant status in children with CKD. Thus, the assessment of dynamic thiol-disulfide levels may contribute to the diagnosis and monitoring of CKD as a marker of OS.