A 56-yr-old man was admitted to our university hospital for severe back pain one month after a resection for lung adenocarcinoma (stage IIIA) without evidence of the adrenal mass. Computed tomography (CT) of the abdomen showed bilateral bleeding of adrenal tumors. Endocrinological laboratory studies showed high plasma ACTH and normal serum cortisol levels with the loss of circadian rhythm. Although plasma ACTH levels increased, there was no cortisol response to administration of human corticotropichormone (hCRH). Core-needle biopsy was performed on the right adrenal tumor and revealed adenocarcinoma cells mimicking a primary lung tumor previously examined. We diagnosed retroperitoneal hemorrhage due to bilateral adrenal gland metastasis from lung adenocarcinoma with adrenal insufficiency. Adrenal metastases most commonly originate from a primary lung tumor, followed by stomach, esophagus and liver/bile ducts. Bilateral adrenal metastases were noted in approximately half of all adrenal metastases patients. Clinically significant adrenal hemorrhage by metastasis is exceedingly rare and non-specific symptoms, such as abdominal, chest or back pain, nausea and vomiting, confusion, weakness, hypotension, shock and high fever, are often observed in these patients. We present a case of massive retroperitoneal hemorrhage and adrenal insufficiency due to adrenal gland metastasis from adenocarcinoma of lung.