Abstract-Therapeutic inertia (TI), defined as the providers' failure to increase therapy when treatment goals are unmet, contributes to the high prevalence of uncontrolled hypertension (Ն140/90 mm Hg), but the quantitative impact is unknown. To address this gap, a retrospective cohort study was conducted on 7253 hypertensives that had Ն4 visits and Ն1 elevated blood pressure (BP) 1999 -2000. 2,3 Despite an increase in the number and tolerability of antihypertensive medications, goal BP has been difficult to attain. Clinical trials, including the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack trial, 4 with 66% control rates and the Controlled Onset Verapamil Investigation of Cardiovascular Endpoints study 5 with 70% control rates have shown that the BP control rates reported in national data can be substantially improved. Of note, the majority of uncontrolled hypertensive subjects in the United States are older individuals with systolic BP (SBP) 140 to 159 mm Hg who are seen an average of 6 times annually in a primary care setting. 6 Even with substantial reductions in the number of unaware and untreated hypertensive patients, controlling BP in Ն70% of treated patients is a vital component of reaching the Healthy People 2010 goal of controlling hypertension in 50% of all affected patients. 7 Hypertension control rates nearly tripled from 10% in 1976 -1980 to 29% in 1988 -1991. 8 The improvements in hypertension control coincided temporally with a large decline in the age-adjusted rates for stroke and coronary heart disease (CHD).Unfortunately, BP control rates have changed little in the past 15 years, especially in women. Patient factors, such as compliance, 9,10 knowledge, 11 and lack of insurance, 12 and system factors, such as limited access to care and medications 13 and lack of appointment reminders, 14 have been cited for the low rates of BP control. Of note, BP control remains suboptimal in systems such as the Veterans Administration where financial barriers to health care are less. 15,16 Physician factors, such as therapeutic inertia (TI), that is, failure of providers to begin new medications or increase dosages of existing medications when an abnormal clinical parameter is recorded, are becoming more evident. TI represents a significant barrier to better hypertension control. TI impacts not only control of BP but of other chronic diseases, including diabetes mellitus and hyperlipidemia. [17][18][19][20][21][22][23][24] Although data suggest that TI contributes to the high prevalence of uncontrolled hypertension, the quantitative impact is not clear. This article examines the impact of TI on