Pheochromocytoma is an uncommon catecholamine-secreting tumor in which resection is often associated with hemodynamic instability (HI). In this study, we aim to clarify the factors affecting surgical HI in patients who underwent surgery with the diagnosis of pheochromocytoma. All patients who underwent surgery with the diagnosis of pheochromocytoma between 2008 and 2015 were analyzed retrospectively. Patients with inconsistent diagnosis or missing outcomes and follow-up data were excluded. A total of 37 patients were included in this study. Patient demographics, operative time, tumor size, period of medical treatment until surgery, catecholamine levels in urine, and HI patterns were analyzed. There were 23 (62%) male and 14 (38%) female patients. Hemodynamic instability occurred in 13 (35%) patients. Overall, HI was higher in patients with tumor size <6 cm (P < 0.02); moreover, urine catecholamine levels were detected significantly higher than a cutoff value of 2000 mu g/24 hours in hemodynamically instable group. In this study, tumor diameter of <6 cm and urine catecholamine levels >2000 mu g/24 hours were associated with HI. Preoperative management is essential for preventing hypertensive crisis and HI before or during surgery.