Cushing's syndrome is characterized by hypercortisolism and impairment of cell-mediated immune function, increasing the risk of opportunistic infection, as occurs in other immunocompromised groups such as organ transplant recipients, patients with lymphoreticular malignancy, or acquired immunodeficiency syndrome. We report a case of a 68-year-old woman who was affected with pneumocystis carinii pneumonia (PCP) 8 years ago and cutaneous nocardiosis this year. The patient was diagnosed with ectopic ACTH syndrome 8 years ago, but no ectopic ACTH secreting focus was found in radiologic imaging studies. She recovered from PCP and cutaneous nocardiosis after antibiotic (trimethoprim-sulfamethoxazole) administration. After the infection resolved, she underwent laparoscopic bilateral adrenalectomy and was not longer hypercortisolemic.