A 46-year-old man was admitted because of hypotension and consciousness disturbance. He was a patient with hemophilia B, and diagnosed as having an AIDS-related complex 2 years prior to admission. On admission he had severe hyponatremia. Hormonal studies revealed that he had Addison's disease. Serum cytomegalovirus (CMV) antibody titers were high, and a CMV antigen was detected in his urine, which suggested CMV adrenalitis caused by an active CMV infection. After the administration of hydrocortisone and ganciclovir, his general clinical condition and biochemical test results were back to normal. However, the adrenal dysfunction was irreversible, despite the treatment with ganciclovir. With an increase in the number of AIDS patients, we have to consider adrenal insufficiency due to a CMV infection in patients with AIDS.