Background: Ideal perioperative management of pheochromocytomas/paragangliomas (pheo) is a subject of debate and can be highly variable. The purpose of this study was to identify potential predictive factors of hemodynamic instability during pheo resection. Methods: A retrospective review of pheo resections from 1992 to 2013 was undertaken. Intraoperative hemodynamics, patient demographics, tumor characteristics, and perioperative management were examined. Postoperative intensive-care admission, myocardial infarction, stroke, and 30-day mortality were reviewed. Linear regression was used to analyze factors influencing intraoperative hemodynamics. Results: During the 20-year study period, 100 patients underwent pheo resection. Postoperative morbidity and mortality was significantly reduced (p = 0.003) in the last 10 years of practice, and there was a trend towards greater morbidity and mortality with intraoperative hemodynamic instability (p = 0.06). The preoperative dose of phenoxybenzamine and the number of laparoscopic procedures has increased in the last decade [59 mg (95 % CI 32–108) to 106 mg (95 % CI 91–124), p = 0.008, and 27 vs. 54 %, p = 0.05, respectively]. Increased preoperative phenoxybenzamine dose was a significant predictor of improved intraoperative hemodynamic stability (p = 0.01). Lack of intraoperative magnesium use resulted in greater hemodynamic instability as preoperative systolic blood pressure increased (p = 0.002). Conclusions: Postoperative outcomes following pheo resection have improved over the last two decades. Preoperative α-blockade plays a significant role in improving intraoperative hemodynamics and post-op outcomes. Increased doses of phenoxybenzamine and utilization of laparoscopic approaches have likely contributed to improved outcomes in the last decade. Intraoperative magnesium use may provide protection against hemodynamic instability and warrants further study.