We report a 21-year-old woman with ectopic ACTH syndrome due to islet cell carcinoma with multiple liver metastases. On admission, she showed Cushingoid appearance (moon face, central obesity etc.) and had acute respiratory distress syndrome due to pneumocystis carinii pneumonia. Laboratory examination revealed marked elevations of plasma ACTH (735 pg/ml) and cortisol (145 microg/dl) with a profound hypokalemia (2.0 mEq/l). She was found to have multiple masses in the liver and a solid mass in the tail of pancreas by abdominal computerized tomography scanning. Treatment with octreotide successfully reduced elevated plasma ACTH and cortisol levels, and she received frequent transhepatic arterial embolization and chemotherapy. The primary pancreatic tumor was surgically removed, revealing islet cell carcinoma which contained high content of ACTH (100 microg/g wet weight) and abundantly expressed proopiomelanocortin and somatostatin receptor subtype-2 mRNAs as determined by Northern blot analysis. Postoperatively, she was free from symptoms for almost one year. However, progressive enlargement of multiple liver metastases refractory to chemotherapy led her to decide on total hepatectomy and liver transplantation from her father. After liver transplantation, she remained almost free from symptoms for almost one year. However, metastases developed to the mediastinal and paraaortic lymph nodes as detected by 111[In] pentetreotide scintigraphy. Eleven months after liver transplantation, she was again treated with octreotide and, 16 months after, with metyrapone, both of which were effective in reducing ACTH and cortisol levels, respectively, until she died of acute respiratory failure. This case of a young female patient with ectopic ACTH-producing islet cell carcinoma of the pancreas was quite unique in that she survived for 5 years despite the acute onset and rapid progression of the multiple liver metastases at least in part due to the long-lasting favorable response to octreotide and living-related liver transplantation.