Human epididymis protein 4 (HE4) has been suggested as a useful new biomarker of lung cancer; however, few relevant large-scale studies have been published. In this study, we evaluated the utility of serum HE4 for lung cancer detection. HE4 levels were measured in serum samples from 100 lung cancer patients, 57 patients with benign lung diseases, and 274 healthy controls by using a chemiluminescent immunoassay, and variations in HE4 levels were analyzed by clinical status such as lung cancer, benign lung disease, and healthy condition, Tumor, Lymph Nodes, Metastasis (TNM) stage, tumor score, and histological cancer type. Lung cancer patients had significantly higher serum HE4 levels than patients with benign lung diseases and healthy controls (P<0.0001). The area under the ROC curve for HE4 was 0.84 (95% confidence interval, 0.78–0.89; P<0.0001) between lung cancer patients and healthy controls. Serum HE4 levels were significantly higher in patients with advanced disease (according to TNM stage) than in healthy controls (P<0.0001). HE4 levels were significantly elevated in patients with tumors of all types, those of different histological subgroups, and those with the smallest tumors (P=0.002). This report supports the potential of serum HE4 as an ancillary diagnostic marker for lung cancer detection.