As a common endocrine and metabolic disorder, polycystic ovary syndrome (PCOS) is mostly associated with an obese phenotype. The present research focuses on the clinical significance of miR-379 in obesity-PCOS and attempts to elucidate its potential mechanisms.Healthy individuals (n = 46), obesity-PCOS (n = 92), and non-obesity PCOS (n = 31) subjects were enrolled. Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to examine the level of serum miR-379. The receiver operating characteristic (ROC) curve and logistic regressions were applied to reveal the diagnostic significance. Dual luciferase reporters were performed to validate the targeting relationships. And cell count kit (CCK-8) assay was used to detect cell proliferation.Serum miR-379 was highly expressed in PCOS patients (P < 0.05), in especially obesity-PCOS patients. Higher miR-379 was associated with greater body mass index (BMI), higher bioavailable testosterone (bT), and greater insulin resistance (IR). Additionally, miR-379 was an independent risk factor for the development of obesity-PCOS. The sensitivity of miR-379 in identifying patients with obesity-PCOS from healthy or non-obesity-PCSO patients was 81.52% and 72.83%, and the specificity was 86.96% and 80.65%. Semaphorin 3 A (SEMA3A) was identified as a target of miR-379 and was reduced in the patients with obesity PCOS (P < 0.05). Inhibition of miR-375 reduced KGN proliferation, but this reduction was partially restored by silencing of SEMA3A (P < 0.05).Elevated miR-379 assists the diagnosis of obesity-PCOS and regulates the proliferation of KGN by targeting SEMA3A engaged in disease development.© 2024 Huang et al.