Notch3 receptor is one of the mammalian Notch family receptors (Notch1-4) which plays an important role in the regulation of cellular proliferation, differentiation, and apoptosis. Overexpression of Notch3 is associated with tumorigenesis. In order to assess the expression of Notch3 in Chinese non-small-cell lung cancer (NSCLC) patients and determine its association with prognosis, we designed a prospective study with five years of follow-up to evaluate Notch3 expression in NSCLC tissues and adjacent non-cancerous normal lung tissues from 131 patients undergoing surgical treatment by immunohistochemistry and western blot analysis. Notch3 had high expression in 67 of 131 cases of NSCLC (51.1 %), which was significantly higher than in adjacent noncancerous lung tissues. Moreover, Notch3 overexpression was significantly correlated with TNM stage (P = 5.41e-07 in squamous cell carcinoma, P = 5.338e-07 in adenocarcinoma) and lymph node metastasis (P = 0.00764 in squamous cell carcinoma, P = 0.01491 in adenocarcinoma). Kaplan-Meier survival analysis showed that the overall survival times in patients expressing Notch3 in NSCLC were shorter. Multivariate analysis further demonstrated that Notch3 was an independent prognostic factor for patients with NSCLC. Therefore, Notch3 might be a useful biomarker to predict the prognosis of patients with NSCLC.