Introduction: Complete resolution of hypertension after adrenalectomy for primary aldosteronism is far from a certainty. This stresses the importance of adequate preoperative patient counseling. The aldosteronoma resolution score (ARS) is a simple and easy to use prediction model only including four variables: ≤ 2 antihypertensive medications, body mass index ≤ 25 kg/m2, duration of hypertension ≤ 6 years and female sex. However, because the model was developed and validated within the USA over a decade ago, the applicability in modern practice and outside of the USA is questionable. Therefore, we aimed to validate the ARS in current clinical practice within an international cohort. Materials and method: Patients who underwent unilateral adrenalectomy, between 2010 and 2016, in 16 medical centers from the USA, Europe (EU), Canada (CA) and Australia (AU) were included. Resolution of hypertension was defined as normotension without antihypertensive medications. Results: In total, 514 patients underwent adrenalectomy and 435 (85%) patients were eligible. Resolution of hypertension was achieved in 27% patients within the total cohort and in 22%, 30%, 40% and 38% of patients within USA, EU, CA and AU, respectively (p = 0.015). The area under the curve (AUC) for the complete cohort was 0.751. Geographic validation displayed a AUC within the USA, EU, CA and AU of 0.782, 0.681, 0.811 and 0.667, respectively. Discussion: The ARS is an easy to use prediction model with a moderate to good predictive performance within current clinical practice. The model showed the highest predictive performance within North America but potentially has less predictive performance in EU and AU.