Although the overall incidence of gastric cancer has steadily declined in the United States, it is estimated that more than 12,000 persons died from gastric cancer in 2003. The incidence of distal stomach tumors has greatly declined, but reported cases of proximal gastric carcinomas, including tumors at the gastroesophageal junction, have increased. Early diagnosis of gastric cancer is difficult because most patients are asymptomatic in the early stage. Weight loss and abdominal pain often are late signs of tumor progression. Chronic atrophic gastritis, Helicobacter pylori infection, smoking, heavy alcohol use, and several dietary factors have been linked to increased risks for gastric cancer. Esophagogastroduodenoscopy is the preferred diagnostic modality for evaluation of patients in whom stomach cancer is suspected. Accurate staging of gastric wall invasion and lymph node involvement is important for determining prognosis and appropriate treatment. Endoscopic ultrasonography, in combination with computed tomographic scanning and operative lymph node dissection, may be involved in staging the tumor. Treatment with surgery alone offers a high rate of failure. Chemotherapy and radiotherapy have not improved survival rates when used as single modalities, but combined therapy has shown some promise. Primary prevention, by control of modifiable risk factors and increased surveillance of persons at increased risk, is important in decreasing morbidity and mortality.