The KLK13 gene is dysregulated in several carcinomas, and its expression levels seem to be associated with disease prognosis. The aim of our study was to investigate the prognostic potential of KLK13 mRNA expression for patients with nonsmall cell lung cancer (NSCLC). Total RNA was isolated from cancerous and normal tissues from a cohort of 128 NSCLC patients. The KLK13 mRNA transcription levels were measured using a sensitive quantitative RT-PCR method. The results were normalized by dividing the KLK13 mRNA values with the geometric mean of mRNA expression from four reference genes: beta-actin, TATA-binding protein, hypoxanthine phosphoribosyltransferase 1, and acidic ribosomal phosphoprotein P0. The malignant tissues from the majority of patients (59.3 %) contained significantly more KLK13 mRNA transcripts than did the paired nonmalignant tissues (median difference 11.1-fold, P = 0.008). KLK13 was expressed at higher levels in females than that in males (P = 0.021). No other statistically significant association with clinicopathological data was observed. Kaplan-Meier survival analyses demonstrated that patients with KLK13-positive tumors survived significantly longer than those with KLK13-negative ones (P = 0.009). KLK13 expression was also shown to be able to stratify high-risk individuals among patients with early disease stages (P = 0.030). Multivariate Cox regression analysis showed that KLK13 expression is a favorable, independent prognostic indicator of overall survival (OS) (P = 0.024). Our results suggest that KLK13 mRNA expression constitutes a novel biomarker for the prediction of overall survival in NSCLC and that its quantitative assessment in tumor tissues can aid in treatment decision making.