OBJECTIVE: Lung cancer (LC) is the highest contributor to cancer-associat-ed mortality worldwide. Approximately 85% of all LC incidences involve non-small cell LC (NS-CLC). Unfortunately, owing to a significant lack of sensitive and robust bioindicators, most pa -tient diagnoses occur at advanced stages of the disease, thereby resulting in extremely poor pa -tient outcomes. Herein, we elucidated the role of interleukin-17A (IL-17A) among NSCLC patients. MATERIALS AND METHODS: Circulating IL-17A content was measured using enzyme-linked immunosorbent assay (ELISA), and its diagnos-tic and prognostic abilities were assessed us-ing the receiver operating characteristic (ROC) curve and Kaplan-Meier analysis, respectively. RESULTS: Our analysis revealed that circu-lating IL-17A levels were significantly augment-ed among NSCLC vs. control samples. Moreover, based on our area under the curve (AUC) analy-sis, circulating IL-17A levels fared considerably better than the standard bioindicator carcinoem-bryonic antigen (CEA) in both testing and valida-tion cohorts. Notably, we also revealed that the circulating IL-17A levels were accurately and reli-ably predicted in early-stage NSCLC patients. Be-sides, we demonstrated a strong correlation be-tween elevated circulating IL-17A expression and worse prognosis among NSCLC patients. CONCLUSIONS: Herein, we demonstrated that circulating IL-17A levels can serve as reli-able and potent diagnostic and prognostic bio-indicators for NSCLC.