The prognostic role of epidermal growth factor receptor (EGFR) and HER2-neu remains controversial in patients with non-small cell lung cancer (NSCLC). We studied the association between the mRNA expression of EGFR, HER2-neu, and survival in primary tumor and matching nonmalignant tissues from 83 patients with NSCLC. Analysis was performed using a quantitative real-time PCR system (Taqman). EGFR and HER2-neu mRNA expression was detectable in all (100%) specimens analyzed. Twenty-nine (34.9%) patients had high HER2-neu expression, and 28 (33.7%) patients had high EGFR expression. A high HER2-neu and EGFR coexpression was detectable in 14 (16.9%) patients. High HER2-neu expression was associated with inferior survival (P = 0.004), whereas high EGFR expression showed a trend toward inferior survival (P = 0.176). The impact of HER2-neu and EGFR coexpression on patients' survival was additive (P = 0.003). Multivariate analysis determined high HER2-neu expression (P = 0.041), and high EGFR/HER2-neu coexpression (P = 0.030) as significant and independent unfavorable prognostic factors. These findings indicate that HER2-neu and EGFR play a crucial role in the biological behavior of NSCLCs. Testing of molecular marker coexpression (EGFR and HER2-neu) improves the estimation of prognosis and appears to define low- and high-risk groups for treatment failure in curatively resected NSCLC.