Cyclic Cushing's disease is a rare clinical entity that is defined as a periodic excessive production of adrenocorticotropic hormone (ACTH) and cortisol. Only 42 cases with cyclic Cushing's disease have been reported in the literature. The diagnosis is very difficult because of the fluctuating secretion of ACTH and cortisol. We report a 78-year-old woman with a pituitary adenoma presenting with cyclic Cushing's disease. In the present case, several interesting issues are pointed out: 1) MRI study detected the presence of an adenoma and selective venous sampling in the cavernous sinus disclosed the hypersecretion of ACTH from a pituitary adenoma. These neuroimaging and endocrinological studies were helpful for the diagnosis, even in the remission phase. 2) The disease was in the long-term remission phase after transsphenoidal Surgery despite the high recurrence rate in this clinical entity, although it recurred four years later. Even in the remission phase of cyclic Cushing's disease, meticulous endocrinological and neuroimaging examinations can reveal the presence of a pituitary adenoma, which should be treated surgically.