Gastric cancer remains difficult to cure except in its superficial spreading stage, that is when it is mucosal or submucosal without any lymph node involvement. Its detection rate should reach 20% of all cancers. Three anatomical types are described: the malignant polyp, the muco-erosive cancer and the ulcero-cancer. The most efficient radiological procedure is fibroscopy rather than radiology: it permits biopsy and brush cytology, two procedures which yield 95% of positive diagnosis. The most frequent precancerous lesion seems to be chronic gastritis and especially gland dysplasia. Early detection may be made easier by defining a poor risk population: gastric ulcer, polyadenoma, partial gastrectomy going back to more than fifteen years, and dyspeptic patients in whom biopsy discovers atrophic gastritis. Such a population should be regularly followed up.