BACKGROUND/AIMS: The plasma DNA concentration of patients with cancer is known to be higher than normal controls. Increased DNA concentration and tumor-specific genes in plasma can be used as tumor markers in some cancers. This study was designed to evaluate whether quantification of plasma DNA concentration by using real-time PCR is useful as a tumor marker in the diagnosis of pancreatic cancer. METHODS: Twenty-four patients (M:F=16:8, mean age; 60.5+/-11.5 years) with pancreatic cancer were recruited for this study. Fifteen patients with chronic pancreatitis and fifteen healthy persons were selected as controls (M:F=26:4, 53.5+/-11.2 years). The concentration of plasma DNA was determined by real-time PCR for telomerase reverse transcriptase gene. RESULTS: Plasma DNA concentration in patients with pancreatic cancer (46.4+/-63.2 ng/mL) was higher than that of chronic pancreatitis (p=0.041) and normal controls (p=0.030). The sensitivity and specificity in detecting pancreatic cancer were 75% and 70% respectively when the cut-off value of plasma DNA concentration was set at 46.9 ng/mL. CONCLUSIONS: Plasma DNA concentration in patients with pancreatic cancer was higher than that of controls. However, its sensitivity and specificity is not high enough to be used as a tumor marker for pancreatic cancer.