BACKGROUND: Patients with adrenal Cushing's syndrome (ACS) typically present with central obesity, hirsutism, hypertension, or glucose intolerance, which can be easily identified by a clinical physician. However, recognizing those with subclinical CS or those with less common symptoms and signs is challenging to the subspecialist, which can lead to delayed diagnosis and treatment. We report a case who presented with repeated vertebral fractures in 6 months. Typical physical appearance of CS was not shown so that suspicions were not raised until severe osteoporosis was demonstrated from bone marrow density study. From our case report, endocrine tests and image survey should always be considered in young patients with repeat vertebral fractures. CASE PRESENTATION: A 48-year-old man presented with severe back pain for 3 months. Second and fifth lumbar spine (L2 and L5) vertebral compression fractures were noted from X-ray and magnetic resonance imaging (MRI), and vertebroplasty was performed by orthopedic surgeons. After 1 month, a newly developed compression fracture of the ninth to twelfth thoracic spine and L4-L5 were noted. Severe osteoporosis was noted from the hip bone mineral density test, and he was referred to an endocrinologist for analysis. Serial endocrine tests confirmed hypercortisolism, and subsequent abdomen MRI showed a left adrenal tumor. ACS was diagnosed. Left laparoscopic adrenalectomy was performed, and the patient received cortisol supplement for 12 months. Thereafter, no new fractures were identified. CONCLUSIONS: ACS should be considered and carefully verified in middle-aged adults who present with severe osteoporosis and repeated vertebral compression fracture.