Purpose: To evaluate the possible association between serum neopterin level and clinical and laboratory findings and their prognostic value of patients with gastric carcinoma. Methods: Serum samples were collected from patients (n = 38) and normal volunteers (n = 39) and stored at -80 degrees C until analyzed. Neopterin, C-reactive protein (CRP), and IL-6 concentration were measured by ELISA. The clinicopathological parameters were determined by reviewing both medical charts and pathological records. Results: Mean neopterin levels were 1.5.26 +/- 11.46 nmol/L in patients with gastric carcinoma and 9.87 +/- 2.90 nmol/L in the control group. Serum neopterin concentrations were significantly higher in patients with gastric carcinoma than in the control group. The number of patients with elevated neopterin level was significantly correlated with stage, gastric wall involvement, the number of metastatic lymph nodes, and the level of serum CRP. The mean neopterin concentrations were significantly elevated in patients older than 60 years, in the presence of venous invasion and increased metastatic lymph node number, and in patients with elevated CRP levels. Neopterin level was also correlated with overall survival as an independent prognostic indoicator. Conclusions: Serum neopterin levels were elevated in patients with advanced gastric cancer and correlated with prognostic parameters and overall survival. Moreover, neopterin measured at the time of diagnosis can be used to predict the survival of gastric carcinoma.