CRP, a marker of chronic inflammation, was found to be higher in women with PCOS compared to controls in 95 studies (n=10,074). Specifically, 62 of 68 meta-analyzed studies found 96% higher CRP in 5235 PCOS women versus 4839 controls. Sensitivity analysis of 37 higher-quality studies confirmed 84% higher CRP in non-obese PCOS women. Thirteen studies measured TNF-α, an inflammatory cytokine, with 7 showing higher levels in PCOS. Nineteen studies measured IL-6, another inflammatory cytokine, with 8 showing higher levels in PCOS. Four studies found higher white blood cell counts in PCOS (n=323) versus controls (n=189). Nine studies examined adiponectin, with meta-analysis of 4 studies showing 48% lower levels in PCOS (n=368) versus controls. These results suggest chronic low-grade inflammation may contribute to PCOS pathophysiology. Further research is needed on the mechanisms involved and potential treatments. The main limitations were differences in methods, ages, BMI and PCOS phenotypes between studies, addressed using sensitivity and subgroup analyses.