Clinical and laboratory finding from three patients with hemodialysis-induced copper intoxication included pancreatitis and myoglobinemia in addition to previously observed feature of this syndrome (gastrointestinal symptoms, leukocytosis, metabolic acidosis, and hemolysis). Copper concentration was measured in samples of serum, erythrocytes, whole blood, and dialysate. In all instances there was a significant hypercupremia following the inciting dialysis. A demonstrated erythrocyte to serum copper concentration gradient documents the ability of the erythrocyte to concentrate copper. It is important to measure the copper concentration in whole blood or erythrocytes in suspected instances of copper intoxication. The possible mechanisms of copper entry into the dialysate include oxidation of metallic copper to cupric ion or contamination of tap water from copper pipes. Copper ion significantly alters erythrocyte metabolism.