Gastric cancer is still a major health problem and a leading cause of cancer mortality despite a worldwide decline in incidence. Environmental and Helicobacter pylori (Hp) acting early in life in a multistep and multifactorial process may cause intestinal type carcinomas, whereas genetic abnormalities are related more to the diffuse type of disease. Primarily due to early detection of the disease, the results of treatment for gastric cancer have improved in Japan, Korea and several specialized Western centres. Surgery offers excellent long-term survival results for early gastric cancer (EGC). Advances in diagnostic and treatment technology have contributed to a trend towards minimal invasive surgery such as endoscopic mucosal resection (EMR) and laparoscopic surgery for selected mucosal cancers. In the Western world, however, more than 80% of patients at diagnosis have an advanced gastric cancer with a poor prognosis. The aim of surgery is complete removal of the tumour (UICC R0-resection), which is known to be the only proven, effective treatment modality and the most important treatment-related prognostic factor. Gastrectomy with preservation of the spleen and pancreas in most cases is the standard procedure. However, at present there is no consensus about the optimal extent of lymph-node dissection. The hypothesis that extended (D2) lymph-node dissection leads to improved survival has not been confirmed in randomized trials. Results from specialized centres and ongoing multi-institutional randomized trials, however, indicate that D2 dissection, with preservation of the spleen and pancreas, can be performed with the same safety as a D1 dissection. Furthermore, in 50% of patients with node-positive disease, the extraperigastric N2 nodes are involved (N2 disease) and thus an R0-resection is achievable only by a D2 node dissection resulting in a 5-year survival of about 30% for such patients. However, even after a D2 node dissection with curative potential, disease recurs in two-thirds of patients with locally advanced gastric cancer (LAGC) and is rapidly fatal. The need for an adjuvant treatment is obvious, but at present there is no such treatment of proven effectiveness. Promising results with preoperative chemotherapy, which increases the R0-resection rate, and intra-or early postoperative intraperitoneal chemohyperthermia to prevent peritoneal dissemination have been reported. However, randomized trials are necessary before these combined treatments become widely accepted. Present data indicate that the treatment of gastric cancer has become more and more sophisticated with a tailored therapy for individual cases. Treatment includes a broad spectrum of therapeutic options from EMR for selected mucosal cancers to aggressive combined treatment for LAGC. Precise knowledge of patterns of recurrence and metastases, critical evaluation of clinicopathologic variables, integration of high technology into diagnosis to predict accurately pre-treatment staging, and the surgeon's ability to perform minimally invasive surgery and D2 node dissection technique are necessary for an appropriate treatment option. All these prerequisites are best ensured by management in experienced surgical oncology units.