The occurrence of rhabdomyolysis and acute renal failure associated with cytomegaloviral infection is rare. A 27-year-old housewife was admitted to our hospital with complaints of thirst, muscle weakness, abdominal pain and oliguria. There was no past history of diabetes, drinking, fever or drug habituation and a negative family history. Laboratory tests revealed myoglobi nuria, hyper-pancreatic type amylaseuria, hyperglycemia, azotemia and highly increased creatine phosphokinase in the plasma. She was treated with hemodialysis and insulin therapy. Serological studies showed a 4-fold increase in cytomegalovirus antibody titers 4 weeks after admission. Muscle biopsy specimens showed hyaline degeneration and infiltration of T cell lymphocytes in the muscle. Renal biopsy specimens showed acute tubular necrosis and some myoglobin casts. No cytomegalovirus antigen was found in renal specimens by immunofluorescence study. From these results, it was determined that a systemic cytomegalovirus infection triggered pancreatitis which caused diabetic ketoacidosis, rhabdomyolysis and acute renal failure. (Internal Medicine 31: 426-430, 1992)