Pregnancy rarely occurs in untreated cases of Cushing's syndrome (CS) , because most of them are infertile due to significant maternal and fetal complications during pregnancy. Diagnosis of CS may be difficult during pregnancy. Since physiological changes of pregnancy are overlapped by classical presentation and biological confirmation of CS. Therefore the high clinical suspicious is needed for diagnosis. We present a 33 years old pregnant woman with a history of chronic hypertension from 10 years ago that referred to Imam Khomeini hospital for uncontrolled hypertension, gestational diabetes and fetal tachycardia at the 30 weeks of gestation. After initial studies abdominal MRI detected a 43 x 35 x 29 mm right adrenal mass. She was treated by anti-hypertensive drugs. But at 31.5 weeks of gestational age cesarean section was performed due to severe preeclampsia. Then two weeks after delivery open right adrenalectomy was carried out without any complications and in the histopathological evaluation benign adrenocortical adenoma was reported. CS is associated with considerable fetal and maternal morbidity and mortality. Selection of treatment method is variable and it depends on gestational age. Medical and surgical approaches have been used in managing CS in pregnancy. Surgical treatment is the first choice for CS which is recommended at the second trimester and in the late pregnancy medical treatment is preferred.