We present a case of fatal adrenal crisis due to isolated adrenocorticotropic hormone (ACTH) deficiency. Autopsy revealed each adrenal gland weighed 0.9 g and the adrenal cortexes were very thin and atrophic. Additionally, cortisol could not be observed in the adrenal cortex by immunohistochemical staining. Furthermore, urine cortisol and 17-OHCS concentration had decreased to a very low level, 20 mg/L and 0.8 mg/L respectively. The anterior pituitary gland was atrophic, and showed fibrosis and lymphocytosis was suspected. Immunohistochemically growth hormone (GH)-stained pituitary gland cells were observed, but there were no cells stained with anti-ACTH antibody. From the history and pathological findings, no other deficiencies of pituitary hormones were evident. Therefore, isolated ACTH deficiency was suspected. Furthermore, as the thyroid gland showed lymphocytic thyroiditis, is was considered that isolated ACTH deficiency was associated with an autoimmune cause. Generally, as patients of chronic adrenocortical insufficiency are exposed to stress and, therefore, have an increased requirement for glucocorticoids, the blood pressure falls, leading to hypovolemic shock called " an adrenal crisis." Without treatment, patients die in crisis within several hours. In our case, the deceased had drunk alcohol without sleep for 2 days. We believe that the stress of drinking and sleeplessness induced adrenal crisis and caused his death.