OBJECTIVE: Self-management of hypertension can reduce and control blood pressure (BP) compared with clinic monitoring. However, self-management relies on patients following an algorithm, which may be variably adhered to. This study reports fidelity of high-risk patients to the self-management algorithm set by the TASMIN-SR trial. METHODS: Patients with hypertension, above target clinic BP and one or more of stroke, diabetes, coronary heart disease or chronic kidney disease, were invited to self-monitor following an individualized self-titration algorithm. Home BP readings and medication change details were submitted monthly for 12 months. Readings downloaded from patients' electronic monitors were compared with written submissions, and protocol fidelity was assessed. RESULTS: Two hundred and seventy-six patients were randomized to self-management and 225 (82%) completed the required training sessions. Of these, 166 (74%) completed self-management. A total of 11385 (89.6%) submitted readings were accurate compared with corresponding downloaded monitor readings. Mean error rate was 5.2% per patient, which increased with age but not comorbidities. Patients made 475 of 683 (69.5%) algorithm-recommended medication changes, equating to nearly three medication changes per patient. Mean SBP for patients who completed training and made all recommended changes dropped from 141 mmHg (95% CI 138.26-144.46) to 121 mmHg (95% CI 118.30-124.17 mmHg) compared with 129 mmHg (95% CI 125.27-136.73 mmHg) for patients who made none. CONCLUSION: Most patients randomized to self-management completed training; however, 36% of these had dropped out by 12 months. Self-monitoring was largely undertaken properly and accurately recorded. Fidelity with self-management was associated with lower achieved SBP. Successful implementation of self-management into daily practice requires careful training and should be accompanied by monitoring of fidelity.