OBJECTIVES: The relationship between compliance and persistence with hypertension therapies and clinical outcomes has not previously been quantified. In addition, little information is available regarding the ‘real-world' effectiveness of hypertension therapies. In this study, we evaluated the impact of compliance and persistence with valsartan (Diovan®) therapy on blood pressure outcomes using office-based effectiveness data. METHODS: We analyzed data from the Geisinger Clinic, a U.S. regional healthcare network with 52 primary care and specialty clinics. Information on patient characteristics and longitudinal data on prescribed medications and use and office blood pressure reading were obtained from the network's electronic health record database. Hypertension status was based on JNC VII guidelines. RESULTS: Increased compliance with use of valsartan therapy (i.e., taking therapy as prescribed) was associated with a significant decrease in systolic and diastolic blood pressure 6 and 12 months after the initial prescription. At 12 months, a 10% increase in compliance resulted in decreases in systolic and diastolic blood pressure of 1.3 and 0.5 mmHg (respectively) and a 17% increase in having controlled blood pressure. Greater persistence with valsartan therapy (i.e., time on therapy following control of blood pressure) was also associated with significant decreases in blood pressure. For each additional month of treatment persistence following blood pressure control, systolic and diastolic blood pressure at one year decreased by 1.4 and 0.5 mmHg, respectively. CONCLUSION: We have demonstrated that both compliance and persistence with valsartan therapy are associated with significant improvements in blood pressure control. Further, having access to office-based blood pressure data, we were able to evaluate treatment effectiveness rather than only efficacy. Improved compliance and persistence with hypertension therapy is likely to result in long-term improvement in patient outcomes, such as decreased cardiovascular complications.