PURPOSE: Islet cell tumors are a rare disease that can be cured by surgical management if they are early diagnosed. However, diagnosis and localization are difficult due to their small size and varied clinical manifestations. We analyzed the clinicopathologic features, the diagnosis and the surgical management of islet cell tumors. METHODS: We retrospectively analyzed the case histories of 30 patients had undergone pancreatic surgery for islet cell tumors between April 1990 and December 1999. RESULTS: The islet-cell tumors included 16 insulinomas, 4 gastrinomas, 1 glucagonoma, one insulin-gastrin secreting tumor, and 8 nonfunctioning tumors. The major clinical manifestations were neuroglycopenic (94%) and adrenergic (75%) symptoms in cases of an insulinoma, abdominal ulcer symptoms (100%) in the cases of a gastrinoma, diabetis mellitus (100%) in the cases of a glucagonoma, and abdominal pain (63%) and a mass (25%) in nonfunctioning tumor. The preoperative tumor localization tools were angiography, transhepatic portal vein sampling, endoscopic ultrasonography, computed tomography, and octreotide scans which had sensitivities of 56%, 71%, 55.5%, 43.3%, and, 25% respectively. The surgical treatments were enucleation (38%) or segmental resection (25%) for insulinomas, pancreaticoduodenectomy with total gastrectomy (25%) or total pancreatectomy (25%) for gastrinomas, and pylorus preserving pancre aticoduodenectomy (38%) or regional pancreatectomy (26%) for nonfunctioning tumors. Malignant islet cell tumors were presenting cases (30%). Two patients died with postoperative complications on post operative day 3 and 35; the others survived during the follow-up period (1 month-10 years). Islet cell tumors with multiple endocrine neoplasm type I occurred in five (17%) cases; in three cases, the tumors were malignant. CONCLUSION: The early diagnosis and vigorous attempt to resect the lesion in islet cell tumors of the pancreas should be carried out for the long-term survival.