OBJECTIVES: The objective of this study was to determine incremental direct expenditures of treating hypertension in the U.S. non-institutionalized population. METHODS: Analysis of 2001 Medical Expenditure Panel Survey (MEPS) data, a national probability sample survey of 33,556 individuals from the civilian non-institutionalized U.S. population was conducted. Hypertensive patients were identified as those with hypertension based ICD-9 codes, i.e., 401-xx-405-xx for medical conditions or medical events, including inpatient visits, outpatient visits, emergency room visits, home-health visits, office-based medical provider visits, and other medical expenses, or patients who self-reported being diagnosed with hypertension by their physician, or patients who were prescribed an anti-hypertensive medication listed in seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of Hypertension, unless there was an indication that the medication was prescribed for a medical condition other than hypertension. Only individuals 18 years of age or older were included. Incremental expenditures for treating hypertension were estimated through least squares regression adjusting for age, gender, race, education, and co-morbidities using the D'Hoore version of the Charlson co-morbidity index. Sample data were projected to the U.S. population and 95% confidence limits for estimates were calculated using the Taylor expansion method. RESULTS: Sample estimates projected to the population indicated that approximately 17.4% of individuals aged 18 years and above in the ambulatory population have hypertension. Total incremental annual direct expenditures for hypertension patients were estimated to be more than $US 54.0 billion in 2001 after adjusting for demographics and co-morbidities. Mean incremental annual direct expenditures for an individual with hypertension was $US 1131. Prescription medicines, inpatient visits, and outpatient visits constituted more than 90% of overall incremental expenditures. CONCLUSIONS: With incremental direct medical expenditures estimated at nearly $US55.0 billion, hypertension expenditures represent a significant amount of health care resource utilization.