BACKGROUND:: The pretreatment prognostic nutritional index has been considered a potential prognostic biomarker in patients with non-small cell lung cancer (NSCLC), but this remains controversial. Therefore, we performed a meta-analysis to systematically assess the prognostic value of the prognostic nutritional index in patients with NSCLC. METHODS:: We systematically searched PubMed, EMBASE, Web of Science, and CNKI. The hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs) were used to evaluate the link between the prognostic nutritional index and the oncological outcomes of patients with NSCLC, including overall survival, disease-free survival/recurrence-free survival, and progression-free survival. RESULTS:: Fifteen studies were included in this meta-analysis. Twelve of these studies explored the association between the prognostic nutritional index and the overall survival of patients with NSCLC. Our pooled analysis indicated that a low prognostic nutritional index was significantly related to adverse overall survival (HR 1.61; 95% CI 1.44, 1.81; P < 0.001). Our results also showed that the prognostic nutritional index was a negative predictor for disease-free survival/recurrence-free survival, and progression-free survival in patients with NSCLC. CONCLUSION:: Our meta-analysis demonstrated that there was a close association between the prognostic nutritional index value and prognosis in NSCLC patients and that the prognostic nutritional index may act as a useful prognostic biomarker in NSCLC patients.