The purpose of this study is to compare two surgical methods of adrenalectomy. One is called PRA(posterior retroperitoneal adrenalectomy), which is performed through 3 or 4 holes at patient's back. The other is LA(laparoscopic adrenalectomy) which is performed through patient's abdominal cavity after making 3 or 4 holes in the abdomen.

Since 1992, transabdominal LA(laparoscopic adrenalectomy) has been a standard method of adrenalectomy. This traditional method has been used widely because this procedure provides wide view of the whole abdomen which is familiar to surgeons. But due to its unique location at retroperitoneum, adrenal is still not easy to approach. So various retroperitoneal approaches were designed and adjusted. Among those, PRA(posterior retroperitoneal adrenalectomy) has showed good outcomes in many institutes. PRA facilitates direct approach to kidney and adrenal gland, and so operative time can be shortened. But there has been no randomized controlled trial between these two methods.

Therefore, as experienced surgeons in both methods, we want to practice this study.

Inclusion Criteria:

• Patients who are expected to have benign adrenal disease at preoperative exams
• Patients who have pheochromocytoma measured less than 5cm, and the other benign adrenal tumors less than 7cm in diameter in preoperative CT scan
• Patients who do not have previous surgery history at the interested quadrant
• Patients who is I or II grade in ASA classification(American society of anesthesiologists' physical status classification)
• Patients who has tolerable liver function and renal function(bilirubin<2.0mg/dl and AST, ALT, serum creatinine within twice of upper normal range, coagulation panel : within normal limit)
• Patients whose BMI(body mass index) is less than 35
• Patients who are supposed to have normal cognitive function
• Patients who signed the consent paper.

Exclusion Criteria:

• Patients who are expected to have malignant or metastatic adrenal tumor at preoperative exams
• Patients who have bilateral adrenal tumors
• Patients who have condition to undergo the other operation at the abdomen together with adrenalectomy
• Pregnant patients
• Patients who have active or uncontrolled infection
• Patients who have medical problems as below
• Uncontrollable hypertension with medication(Systolic BP>150 or diastolic BP>100)
• Angina, congestive heart failure, acute myocardial infection
• History of coronary angioplasty or Coronary artery bypass graft surgery
• History of stroke, transient ischemic attack with sequela