Introduction:To date, little research has been published on the impact that the transition from paper-based record keeping to the use of electronic health records (EHR) has on performance on clinical quality measures. This study examines whether small, independent medical practices improved in their performance on nine clinical quality measures soon after adopting EHRs.Methods:Data abstracted by manual review of paper and electronic charts for 6,007 patients across 35 small, primary care practices were used to calculate rates of nine clinical quality measures two years before and up to two years after EHR adoption.Results:For seven measures, population-level performance rates did not change before EHR adoption. Rates of antithrombotic therapy and smoking status recorded increased soon after EHR adoption; increases in blood pressure control occurred later. Rates of hemoglobin A1c testing, BMI recorded, and cholesterol testing decreased before rebounding; smoking cessation intervention, hemoglobin A1c control and cholesterol control did not significantly change.Discussion:The effect of EHR adoption on performance on clinical quality measures is mixed. To improve performance, practices may need to develop new workflows and adapt to different documentation methods after EHR adoption.Conclusions:In the short term, EHRs may facilitate documentation of information needed for improving the delivery of clinical preventive services. Policies and incentive programs intended to drive improvement should include in their timelines consideration of the complexity of clinical tasks and documentation needed to capture performance on measures when developing timelines, and should also include assistance with workflow redesign to fully integrate EHRs into medical practice.