Background: Arterial hypertension is common in adults with repaired coarctation of the aorta, and is associated with several severe complications. Aims: This study aimed to investigate the prevalence of poorly controlled (amp;gt;= 140/90 mmHg) blood pressure among patients with diagnosed hypertension and to identify associated factors. Methods: In the national register for CHD, adults with repaired coarctation of the aorta and diagnosed hypertension - defined as a registry diagnosis and/or use of anti-hypertensive prescription medication - were identified. Logistic regression analysis was used to identify variables associated with poorly controlled blood pressure. Results: Of the 243 included patients, 27.2% were female, the mean age was 45.4 +/- 15.3 years, and 52.3% had poorly controlled blood pressure at the last registration. In a multivariable model, age (years) (OR 1.03, CI 1.01-1.06, p = 0.008) was independently associated with poorly controlled blood pressure and so was systolic arm-leg blood pressure gradient in the ranges [10, 20] mmHg (OR 4.92, CI 1.76-13.79, p = 0.002) to amp;gt;20 mmHg (OR 9.93, CI 2.99-33.02, p amp;lt; 0.001), in comparison with the reference interval [0, 10] mmHg. Patients with poorly controlled blood pressure had, on average, more types of anti-hypertensive medication classes prescribed (1.9 versus 1.5, p = 0.003). Conclusions: Poorly controlled blood pressure is common among patients with repaired coarctation of the aorta and diagnosed hypertension, despite what seems to be more intensive treatment. A systolic arm-leg blood pressure gradient is associated with poorly controlled blood pressure, even at low levels usually not considered for intervention, and may be an indicator of hypertension that is difficult to treat.