The purpose of this investigation was to describe the clinical presentation of nine patients with calciphylaxis involving the proximal lower extremities or trunk and to compare the clinical characteristics of these patients with those of 347 hemodialysis patients from the same geographic area. Patients were identified primarily through a computer search of pathology records, identifying patients with the term "calciphylaxis" in the biopsy report. All patients had pathologic specimens consistent with calciphylaxis. All the calciphylaxis patients were white and were markedly obese. While two patients had markedly elevated parathyroid hormone levels, most patients did not show severe derangements of calcium phosphate metabolism compared with other dialysis patients. A logistic regression model identified body mass index and low serum albumin 3 months before diagnosis as being highly associated with a diagnosis of calciphylaxis. Diabetes mellitus and parameters of calcium-phosphate metabolism were not significantly associated with proximal calciphylaxis. These findings suggest that white race, morbid obesity, and poor nutritional status are associated with proximal calciphylaxis in dialysis patients.