Purpose. In this study we tried to determine the association between body-mass index (BMI), survival rate, and the stage of tumor at the time of diagnosis in patients with gastric cancer. Methods. A total of 270 gastric cancer patients' hospital records were retrospectively evaluated. Patients were grouped according to their BMI at the time of tumor diagnosis. Tumor stages at admission were compared according to their BMI values. Results. There were no differences in OS among BMI subgroups (p = 0.230). The percent of patients with stage III tumor was significantly higher in nonobese while the percent of stage IV tumor was surprisingly higher in obese patients (p was 0.011 and 0.004, resp.). Percent of patients who did not have any surgical intervention was significantly lower in overweight and obese patients than normal and/or underweight patients. Conclusions. At the time of diagnosis, obese patients had significantly higher percent of stage IV tumor than nonobese patients. Despite of that, there were no differences in survival rates among BMI subgroups. Our study results are consistent with "obesity paradox" in gastric cancer patients. We also did not find any relationship between BMI and localization of gastric tumor.