A better understanding of the process of gastric cancer development would undoubtedly be helpful in diagnosis and treatment. However, there is little literature available concerning the natural history of elevated type gastric cancer in humans and this disease had not been systematically investigated. In this study the natural history of elevated type human gastric cancer was retrospectively investigated in 12 radiologically followed-up patients. The cases were divided into two groups according the whether obvious abnormal findings were absent (group A, n = 5) or present (group B, n = 7) at initial examination. Clinico-pathological features, including outcomes and DNA content of the tumours in both groups, were investigated and compared. Although the mean period between the initial and final examinations was significantly shorter in group A (19.6 +/- 11.7 months) than in group B (43.4 +/- 17.3 months), tumour size was significantly larger in group A (5.5 +/- 2.5 cm) than in group B (2.4 +/- 2.5 cm). Furthermore, group A showed deeper neoplastic cell invasion and worse outcomes. The DNA content of two cases in group A and four cases in group B was examined. One case in group A showed and aneuploid pattern, while all of those in group B showed a diploid pattern. These results indicate that the tumours in group A grew much faster than those in group B, which suggests the presence of two different patterns of development in elevated type gastric cancer.