The benign adrenal cortical adenoma usually secretes cortisol and its size is less than 3 cm in diameter. Though adrenal cortical carcinoma also secretes cortisol and other steroid hormones, its size is usually over 6 cm. We present a huge glucocorticoid producing adrenal cortical adenoma ($15{ imes}11{ imes}12 cm$), which was diagnosed by NP-59 scan and confirmed by surgery, with a review of the literature.