Background There is little known about the clinicopathological features and the predictors of survival in extremely young adult patients aged 18-30 years. The aim of this study was to identify clinicopathological features and clinical outcomes for the overall population and for a resectable subgroup of gastric cancer patients aged 18-30 years.Methods From January 2004 to December 2010, 207 patients aged between 18 and 30 years old were diagnosed with gastric cancer and treated at the Asan Medical Center. Clinical findings, histopathological parameters and outcomes were reviewed retrospectively. Patients were further divided into 2 groups according to tumor resectability and then clinicopathological factors that affect tumor resectability and clinical outcomes were analyzed. Results Clinicopathological characteristics of study population showed a predominance of females, undifferentiated tumors, diffuse-type cancers, and advanced gastric cancer. The overall resectability rate was 70.0 % and the median follow-up period was significantly longer in the resectable tumor group (P \ 0.001). Significant prognostic predictors for overall survival in overall patients were higher CEA levels (P = 0.016), larger tumor size (P \ 0.001), unresectability (P = 0.006), and presence of lymphovascular invasion (P = 0.012) in a multivariate analysis. Significant prognostic factors for overall survival in patients with resectable disease included larger tumor size ([4 cm), lymphovascular invasion and higher CEA level in the multivariate analysis. Conclusions Gastric adenocarcinomas in young adult patients aged 18-30 years have unique clinicopathological features. Early detection in a resectable state and subsequent complete resection could increase survival period in young patients with gastric cancer.