The diagnostic modalities and management of gastrinoma/Zollinger-Ellison syndrome (ZES) have been markedly modified and improved over the past 15 years. To evaluate the present status of this disease, in terms of various clinicopathologic features, we collected 359 Japanese cases of gastrinoma/ZES from the literature. We found a decreasing incidence (from 74.7% in 1965-1980 to 34.2% in 1981-1995) of multiple surgeries and a decreasing rate (from 94.3% in 1965-1980 to 83.5% in 1981-1995) of ZES associated with gastrinoma. There was an increasing rate (from 12.6% in 1965-1980 to 48.9% in 1981-1995) of correct preoperative diagnosis. (All these differences were significant; P < 0.01). In 1981-1995, there was a high incidence (51. 1%) of small tumors (20 mm or less) and a high rate (39.5%) of metastases, and a relatively favorable postoperative outcome (10-year survival rate of 63.7%); P < 0.05. The diagnosis and treatment of gastrinoma/ZES have been markedly improved by increased rates of curative surgery, and more favorable postoperative outcomes will be expected in decades to come.