BACKGROUND: Control of hypertension has improved nationally with focus on identifying and treating elevated blood pressures (BPs) to guideline recommended levels. However, once BP control is achieved, the frequency in which BP falls out of control and the factors associated with BP recidivism is unknown. In this retrospective cohort study conducted at 2 large, integrated health care systems we sought to examine rates and predictors of BP recidivism in adults with controlled hypertension. No change for methods, results and conclusion. METHODS: Patients with a prior diagnosis of hypertension based on a combination of International Classification of Diseases, Ninth Revision, codes, receipt of antihypertensive medications, and/or elevated BP readings were eligible to be included. We defined controlled hypertension as normotensive BP readings (<140/90 mmHg or <130/80 mmHg in those with diabetes) at 2 consecutive primary care visits. We then followed up patients for BP recidivism defined by the date of the second of 2 consecutive BP readings >140/90 mmHg (>130/80 mmHg for diabetes or chronic kidney disease) during a median follow-up period of 16.6 months. Cox proportional hazards regression assessed the association between patient characteristics, comorbidities, medication adherence, and provider medication management with time to BP recidivism. RESULTS: A total of 23,321 patients with controlled hypertension were included in this study. The proportion of patients with hypertension recidivism was 24.1% over the 16.6-month study period. For those with BP recidivism, the median time to relapse was 7.3 months. In multivariate analysis, those with diabetes (hazard ratio [HR] 3.99, CI 3.67-4.33), high normal baseline BP (for systolic BP HR 1.03, CI 1.03-1.04), or low antihypertensive medication adherence (HR 1.20, CI 1.11-1.29) had significantly higher rates of hypertension recidivism. Limitations of this work include demographics of our patient sample, which may not reflect other communities in addition to the intrinsic limitations of office-based BP measurements. CONCLUSIONS: Hypertensive recidivism occurs in a significant portion of patients with previously well-controlled BP and accounts for a substantial fraction of patients with poorly controlled hypertension. Systematic identification of those most at risk for recidivism and implementation of strategies to minimize hypertension recidivism may improve overall levels of BP control and hypertension-related quality measures.