Our previous studies have shown that platelet endothelial cell adhesion molecule-1 (PECAM-1), a member of the immunoglobulin superfamily, is a critical mediator of anchorage-independent growth and anoikis resistance in lung carcinoma cells. The purpose of this study was to analyze the protein expression of PECAM-1 in non-small-cell lung carcinoma (NSCLC) tissues and its clinical significance in NSCLC patients. By immunohistochemical analysis, high microvessel density (MVD) of PECAM-1 was detected in the stromal tissues of NSCLC. The MVD of PECAM-1 was strongly correlated with the N stage (p = 0.029), M stage (p = 0.001) and clinical stage (p = 0.001) of NSCLC patients. Survival analysis revealed high MVD of PECAM-1 in both primary NSCLC lesions and metastatic lymph node tissues, and these results were found to be significantly correlated with poor overall survival in NSCLC patients (p < 0.001 and p = 0.021, respectively). Moreover, patients with high PECAM-1 MVD had worse overall survival in either adenocarcinoma or EGFR mutation subgroups. Multivariate analysis revealed that the MVD of PECAM-1 was an independent prognostic factor for NSCLC patients. The MVD of PECAM-1 is also a potential predictor for NSCLC patients treated with first-line platinum-based doublet chemotherapy, as high PECAM-1 MVD correlated with worse overall survival. Our results demonstrated that MVD of PECAM-1 could be a potential prognostic factor and therapeutic target in NSCLC.