Metastin, which is a 54-residue peptide coded by KiSS-1 gene, is an endogenous ligand to a G-protein-coupled receptor GPR54. Metastin suppresses a malignant tumor to metastasize and regulates secretion of gonadotropine releasing hormone. Physiological action of metastin has been focused on in oncology. It is reported that less KiSS-1 gene and more hOT7T175 gene which codes GPR54 are expressed in pancreatic cancers than in normal pancreatic tissues; however, there is no study that investigates the relationship between clinicopathological characteristics and plasma metastin concentration in pancreatic cancer patients. The purpose of this study was to investigate the relationship between plasma metastin-like immunoreactive substance (LI) levels and clinical characteristics in pancreatic cancer patients. Thirty-three patients with pathologically confirmed pancreatic cancer before or just after treatments and 24 healthy volunteers were included in the study. Patients were grouped according to the International Union Against Cancer TNM classification. Plasma metastin-LI was measured by enzyme immunoassay. The plasma metastin-LI levels of cancer patients were significantly higher when compared with healthy volunteers. Significant relationship was not found between the plasma metastin-LI levels and the clinicopathological factors such as tumor size, invasion, lymph node metastasis and distant metastasis. The plasma metastin levels may be a significant biomarker to predict the presence of pancreatic cancer and could be used in pancreatic cancer screening.