Current clinical guidelines suggest that adrenal venous sampling (AVS) may not be mandatory in young patients with primary aldosteronism (PA) and a solitary adrenal adenoma on imaging.The aim of this study was to further elucidate whether conventional imaging alone is sufficient to distinguish unilateral from bilateral PA among patients aged 40 years or younger.This was a retrospective study where data from 45 patients with PA, aged between 26 and 40 years, who underwent successful AVS between 2005 and 2019, were analyzed. Results concerning laterality on imaging studies and AVS were recorded. Outcome in surgically treated patients was assessed according to the Primary Aldosteronism Surgical Outcomes (PASO) criteria.In four of 25 patients with unilateral aldosterone production according to AVS, CT inaccurately suggested bilateral disease. Following unilateral adrenalectomy, all four patients showed complete clinical success. Five of 20 patients with bilateral aldosterone production according to AVS had a solitary adrenal nodule (8-19 mm) on imaging. Two of these five patients were treated with unilateral adrenalectomy, neither having complete biochemical and/or clinical success postoperatively. Two of 16 patients younger than 35 years had discordant results, one with unilateral, and one with bilateral aldosterone production, according to AVS.Imaging studies inaccurately predicted laterality in a significant number of young patients with PA. In contrast to current clinical guidelines, our results support AVS for subtype evaluation in young adults with PA, including patients 35 years or younger.