CONTEXT:Adrenal vein sampling (AVS) is recommended in all patients with hyperaldosteronism to whom surgery would be offered if the results indicated unilateral hypersecretion. OBJECTIVE:To assess the performance of AVS against radiological findings and to evaluate the Endocrine Society's Practice Guidelines for diagnostic cut-offs. PATIENTS:Retrospective study of 41 patients with hyperaldosteronism who underwent both AVS and computed tomography (CT) imaging. RESULTS:CT and AVS results were concordant in 73.7%. Unilateral lesions on CT had a greater positive predictive value (85%) than non-unilateral lesions (50%). In patients with subsequently confirmed adrenal adenomas, a lateralisation ratio >2 when comparing cortisol-corrected aldosterone ratios from the affected versus unaffected side was 100% sensitive. Patients who were managed surgically experienced significant reductions in blood pressure and medication burden and 46% were cured. CONCLUSIONS:AVS is important in establishing unilateral or bilateral adrenal secretion of aldosterone in patients with primary hyperaldosteronism. However, it may not be essential for the work-up in patients below the age of 40, in whom adrenal incidentalomas adrenal incidentalomas are known to be rarer, and a unilateral lesion on CT therefore has a greater positive predictive value.