Human complement factor H (CFH), a central complement control protein, is a member of the regulators of complement activation family. Recent studies suggested that CFH may play a key role in the resistance of complement-mediated lysis in various cancer cells. In this study, we investigated the role of CFH in human lung cancer. Expression of CFH was analyzed in lung cancer cell lines by RT-PCR, Western blotting and immunofluorescence. In primary lung tumors, the protein expression of CFH was evaluated by immunohistochemistry (IHC) on tissue microarray (TMA). Binding of CFH to lung cancer cells was detected by flow cytometry. mRNA expression of CFH was detected in 6 out of 10 non-small cell lung cancer (NSCLC) cell lines, but in none of the small cell lung cancer (SCLC) cell lines. In line with Western blotting, immunofluorescence analysis demonstrated CFH protein expression in 3 NSCLC cell lines, and the immunoreaction was mainly associated with cell cytoplasm and membrane. In primary lung tumors, 54 out of 101 samples exhibited high expression of CFH and high expression was significantly correlated with lung adenocarcinoma (p=0.009). Also, in adenocarcinoma of the lung, Kaplan-Meier survival analysis showed a tendency that CFH-positive tumors had worse prognosis in comparison to CFH-negative tumors (p=0.082). Additionally, shorter survival time of patients with adenocarcinoma (<20 months) was associated with higher staining of CFH (p=0.033). Our data showed that non-small cell lung cancer cells expressed and secreted CFH. CFH might be a novel diagnostic marker for human lung adenocarcinoma.