Aim <p>Oxidative stress is considered to play a role in the etiopathogenesis of bipolar disorder. This study aimed to compare oxidative stress indicators among bipolar disorder patients in different mood states and healthy controls.</p> Method <p>The sample included 101 bipolar patients (33 euthymic, 36 depressive, and 32 manic) and 29 healthy controls. Total antioxidant status (TAS), total oxidation status (TOS), superoxide dismutase (SOD), glutathione (GSH), thioredoxin reductase 1 (TrxR1), and peroxiredoxin 1 (PRDX1) levels were measured, along with SOD2 rs4880 and GPX3 rs3792797 single nucleotide polymorphisms (SNPs).</p> Results <p>Compared to controls, bipolar patients had higher TAS (<i>p</i> = 0.031), TrxR1 (<i>p</i> &lt; 0.001), and PRDX1 (<i>p</i> &lt; 0.001) levels, and lower GSH levels (<i>p</i> &lt; 0.001). No significant group differences were found for TOS (<i>p</i> = 0.776), SOD (<i>p</i> = 0.086), or OSI (<i>p</i> = 0.312). Among mood states, TAS, GSH, TrxR1, and PRDX1 levels did not differ significantly. TrxR1 and PRDX1 showed significant diagnostic performance in distinguishing bipolar disorder (<i>p</i> &lt; 0.001 for both). While GPX3 rs3792797 SNP did not differ between patients and controls, a significant difference was found for SOD2 rs4880, with AA allele carriers exhibiting higher SOD levels.</p> Conclusion <p>This study is among the few investigating oxidative stress markers across different mood episodes in bipolar disorder and the first to examine TrxR1 and PRDX1. Findings suggest TrxR1 and PRDX1 as potential novel biomarkers in the pathophysiology of bipolar disorder.</p> Clinical trial number <p>Not applicable.</p>