Purpose: The prevalence of gastric cancer in the elderly is increasing. The purpose of this study was to clarify factors related to morbidity following gastric cancer surgery in elderly patients. Materials and Methods: For this study, data from 411 patients who underwent curative gastrectomies with lymph node dissections between March 2010 and January 2013 were retrospectively studied using a prospectively designed database. Patients were divided into 2 groups (<70 years vs. ${geq}70$ years). For each group, perioperative factors were analyzed to determine if they were associated with postoperative morbidity and mortality. Results: Comorbidities were more prevalent in the elderly group (${geq}70$ years). Intraoperative and postoperative transfusions were also more frequently required in the elderly group. There was no significant difference in the number of retrieved lymph nodes between the 2 groups (44.3 vs. 46.6 nodes). In a comparison of the elderly versus non-elderly groups, the postoperative morbidity rates were 22.7% versus 8.9% (P<0.001) and the postoperative mortality rates were 4.2% versus 0% (P=0.002), respectively. Of the possible non-surgical complications, pulmonary problems were predominately found in the elderly group (P<0.001). Surgical complications were evenly distributed between the 2 groups (P=0.463). Postoperative morbidity was significantly associated with older age and postoperative transfusion. Multivariate analysis showed that higher body mass index (BMI) and postoperative transfusion were important factors associated with postoperative complications in the elderly group. Conclusions: Pulmonary complications were frequently problematic in elderly patients. Higher BMI and postoperative transfusion were significant risk factors for postoperative complications in elderly patients with gastric cancer.