A 75-year-old woman had tumors in her pituitary, thyroid and left adrenal gland. Plasma ACTH and cortisol levels were both mildly elevated. Both plasma ACTH and cortisol concentrations were partially suppressed by 1 mg of overnight dexamethasone suppression test, while both were inhibited with a dosage of 8 mg dexamethasone. Plasma ACTH and cortisol levels were increased in response to human CRH and desmopressin. Together with the observation of pituitary microadenoma, the patient had a pituitary ACTH-producing tumor. The patient, however, had no typical Cushingoid features, hypertension, or impaired glucose tolerance, suggesting that the tumor had an autonomic ACTH secretion that was insufficient for expressing clinical symptoms, the so-called preclinical Cushing’s disease. A case of preclinical Cushing’s disease is extremely rare. Further, the patient had thyroid papillary carcinoma and non-functioning adrenal tumor. Molecular genetic analysis demonstrated a polymorphism of the menin gene in the patient. Even without Cushingoid features in pituitary incidentaloma, we concluded that the elevated ACTH and cortisol levels should be followed up by CRH, desmopressin and dexamethasone suppression tests. This patient with preclinical Cushing’s disease would be observed whether the physical conditions in the patient develop to overt Cushing’s disease.