We present an unusual patient who simultaneously had severe renal artery stenosis RAS and Cushing's syndrome. The case highlights the difficulty of reaching a specific diagnosis of Cushing's syndrome and the possible interaction between Cushing's syndrome and some other concurrent illnesses that this patient had. A 37-year old man presented with severe hypertension HTN and uncontrolled diabetes mellitus DM without clear physical signs of Cushing's syndrome. He was found to have severe osteoporosis, proximal myopathy, several cutaneous warts, tinea versicolor, and chronic viral hepatitis. Captopril-stimulated renal scan and renal artery angiogram revealed severe RAS. Partial balloon dilatation of RAS led to improvement in HTN. Unexpectedly, urine free cortisol 24 hour was found extremely high. Serum adrenocorticotropic hormone ACTH was also elevated and high dose dexamethasone suppression tests were inconclusive. Several imaging studies failed to localize the source of ACTH. Despite normal MRI of the pituitary gland, bilateral inferior petrosal sinus sampling IPSS localized the source of ACTH secretion to the right side of the pituitary gland and right anterior hemihypophysectomy resulted in cure of Cushing's disease, HTN, DM, and tinea versicolor with significant improvement in cutaneous warts, osteoporosis, and chronic hepatitis. In conclusion, RAS and Cushing's syndrome may occur together. Significant hypercortisolemia can occur without clear signs of Cushing's syndrome. Controlling hypercortisolemia is of paramount importance when treating chronic infections in patients with Cushing's syndrome.