Objective: Resistant hypertension is defined as the failure to reach blood pressure (BP) goals while treated at adequate doses with three or more antihypertensive agents (AHYs) where one is a diuretic. Clinical trials have found that 2-15% of treated patients have resistant hypertension. The exact prevalence of resistant hypertension in clinical practice is unknown. This analysis evaluates the prevalence of resistant hypertension in a real-world setting. Methods: Hypertensive patients aged 18 and older were identified from the General Electric Electronic Medical Records (EMR) database during the period of November 1, 2002 to November 30, 2005. Resistant hypertension was defined as a blood pressure reading over 140/90 mmHg (130/80 mmHg for patients with diabetes or kidney disease) within one year after the last AHY agent was prescribed during a treatment observation window of November 1, 2003 to November, 2004. Results: A total of 29,474 hypertensive patients were identified with an average age of 63.3 years (SD ±13.3) and 60.9% were female. Of these 21,460 (72.8%) were treated with at least one AHY and 3584 (12.2%) were treated with three or more AHYs including a diuretic. Overall, 19,202 (65.6%) of the population had uncontrolled hypertension, and 2670 (9.1% overall or 12.4% of the treated population) had resistant hypertension. Resistant hypertension occurred in 70.9% of those treated with three AHYs including a diuretic and in 82.3% of those treated with four or more AHYs including a diuretic. The prevalence of diabetes and/or kidney disease was higher in patients with resistant hypertension (37.8% vs. 22.9%; p<.001). Conclusion: This study provides real-world evidence that resistant hypertension is a common treatment concern in the management of hypertension. Additional research to better understand patient characteristics, long term outcomes, and optimal treatment options in the management of resistant hypertension is warranted.