Background: Polycystic ovarian syndrome (PCOS) is a multifactorial endocrine disorder affecting women of reproductive age. The syndrome is characterized by anovulation, hyperandrogenism, abdominal obesity and infertility. Literature emerging from EuroAmerican populations has reported associations between PCOS and biochemical characteristics, oxidative stress and psychological burden indices. In the Arab region, frequent research has been conducted about some aspects of PCOS, despite a heterogeneity in scope and methodology; however, there is still a dearth of studies regarding the association between PCOS and oxidative stress and psychological burden. Aim: This study was designed to provide a comparative assessment of the biochemical characteristics, oxidative stress and psychological burden indices of women with and without PCOS in Oman and to explore the risk factor profile of PCOS after adjusting for potential confounders. Methods: A case-control study was conducted at Sultan Qaboos University Hospital among women aged 16–49 years. The study included a case group of 102 women diagnosed with PCOS (as per the Rotterdam 2003 criteria) and a control group of 110 women without PCOS. Information about sociodemographic and anthropometric characteristics, clinical and obstetric history, co-morbidities, family history of comorbidities, selected vitamin and mineral intake and biochemical parameters were gathered from three sources: personal interviews with the participants, a review of the hospital records and laboratory assays in the hospital. From this cohort, two subgroups were recruited. The first subgroup consisted of 96 participants (51 PCOS cases and 45 controls) in whom serum oxidative biomarker levels were measured using colorimetric and fluorometric assays. The other subgroup consisted of 112 participants (52 PCOS cases and 60 controls) in whom psychological burden indices were evaluated using the Depression, Anxiety and Stress Scale 21 questionnaire. Data analysis was conducted using the Statistical Package for the Social Sciences and Graph Pad Prism 5 software. Results: PCOS women exhibited significant clinical characteristics of irregular menses, hirsutism and acne compared to non-PCOS women (p<0.05). In terms of anthropometric measurements, the mean body mass index, waist circumference and waist-to-hip ratio were significantly higher among PCOS women compared to non-PCOS women (p<0.05). Proportionately, PCOS women had significantly lower parity (p=0.005) compared to the control group. According to gonadotropic and sex hormone parameters, the proportion of women with high follicle stimulating hormone levels was significantly lower in the PCOS group compared to the control group (12.7% vs 34.5%, p=0.001). On the contrary, the proportion of women with high luteinizing hormone levels was significantly greater in the PCOS group compared to the control group (22.5% vs 7.3%, p=0.003). A similar pattern was observed for high testosterone levels (18.6% vs 1.8%, p<0.001). Moreover, the proportion of women with low progesterone levels was significantly higher in the case group than the control group (68.6% vs 38.2%, p<0.001). Proportionately, there were significantly fewer women with low estradiol levels in the PCOS group compared to the control group (7.8% vs 27.3%, p=0.001). In terms of insulin resistance parameters, the proportion of women with high fasting insulin levels was significantly greater in the case group compared to the control group (9.8% vs 1.8%, p=0.01). In contrast, the proportion of women with high fasting blood sugar levels was significantly lower in the PCOS group compared to the control group (22.5% vs 34.5%, p=0.05). After delineating the confounding effects of diabetes mellitus and metformin intake, an increased association was observed between high insulin levels (crude odds ratio [OR]=6.14) and high glycated hemoglobin levels (crude OR=1.28) and PCOS. According to their lipid profile, the proportions of women with elevated low-density lipoprotein cholesterol (12.7% vs 7.2%, p=0.001), elevated very-low-density lipoprotein cholesterol (22.5% vs 5.5%, p<0.001) and elevated triglycerides (3.9% vs 0%, p=0.05) levels were significantly higher in the case group compared to the control group. Adjusted estimates for the associations between PCOS and selected risk factors showed a significantly increased risk of PCOS with a family history of PCOS (OR=2.76, 95% confidence interval [CI]\1.46, 5.21, p=0.002). In addition, the risk of PCOS tended to be higher in association with school-level education compared to university-level education (OR=1.56, 95%CI=0.69, 3.53). Moreover, there was a significant reduction in PCOS risk with advanced age (p=0.02). Nonetheless, the strength of the associations with PCOS risk tended to be reduced for those who were unemployed, single and had a lower monthly family income, as the associations were statistically non-significant (p>0.05). Among the oxidative stress parameters, the activity levels of glutathione peroxidase (9174.5 U/L vs 7498.7 U/L) and glutathione reductase (499.9 U/L vs 435.1 U/L) appeared to be higher among PCOS women compared to non-PCOS women; however, no statistically significant differences were observed between the two groups (p>0.05). On the contrary, glutathione levels were significantly lower among PCOS women compared to non-PCOS women (6.3 mg/ml vs 11.2 mg/ml, p=0.006). Also, total antioxidant capacity (TAC) levels appeared to be slightly lower among PCOS women compared to non-PCOS women; however, this difference was statistically non-significant (3.8 mmol/L vs 4.0 mmol/L, p>0.05). A correlation analysis showed a significant negative correlation between estradiol and TAC levels in the total sample (r=-0.284, p=0.005). In terms of psychological burden indices, the crude ORs generated by logistic regression models indicated slight increases in the risks of depression, anxiety and stress among PCOS women compared to non-PCOS women. A similar pattern was observed after adjusting for possible confounders (age and education level). Hence, the adjusted ORs were 1.10 (95%CI=0.50, 2.43) for depression, 1.09 (95%CI 0.47, 2.52) for anxiety and 1.45 (95%CI= 0.68, 3.12) for stress; however, no statistical differences were observed along the three psychological distresses between the two groups (p>0.05). Conclusion: Overall, this study provides supportive evidence that there is an increased risk of PCOS with younger age, lower education levels and a positive family history of PCOS. This study showed that PCOS women in Oman are at a higher risk of infertility, abdominal obesity, insulin resistance, oxidative stress and psychological disturbances. The risk factor profile and complications associated with PCOS in Oman may be of use for the purposes of primary screening and early prevention. Keywords: Polycystic ovarian syndrome, Oman, oxidative stress, insulin resistance.