It is suggested that adrenomedullin (AM) plays a role in lung carcinogenesis although, to confirm this suggestion, further clinical studies are needed to determine its relationship with prognosis in lung cancer. Archived 50 paraffin-embedded tumor samples of the lung were retrospectively evaluated for AM expression by immunohistochemistry and analyzed for a possible correlation with patient characteristics and survival. Quantitation of immunoreactivity was accomplished using an immunohistochemical scoring system. The pulmonary resection specimens contained 22 squamous cell carcinomas, 15 adenocarcinomas, and 13 small cell carcinomas. Non-small cell carcinomas of the lung were more likely to express AM than small cell carcinomas of the lung. Ninety-one percent of squamous cell carcinomas and 87% of adenocarcinomas expressed AM at a moderate to strong level and grade 2-4 (30-100%), which were significantly higher from the non-neoplastic lung tissue. Twenty-three percent of small cell carcinomas of lung expressed AM. Interestingly, AM immunoreactivity was essentially weak and grade 1 (<%30) in this group. AM expression is upregulated in non-small cell carcinomas of the lung, whereas it is downregulated in small cell carcinomas and non-neoplastic lung tissues. AM expression did not show any correlation with the differentiation of the tumor, the stage of cancer, and the overall survival of patients. These results did not support the role of adrenomedullin as an independent survival factor for lung cancer. However, AM inhibition in conjunction with other anti-angiogenic agents may be useful in the prevention and treatment of malignancies.