Abstract Purpose Normal basal plasma aldosterone concentration (PAC) reflects mild aldosterone excess compared to high basal PAC. We previously reported lower risk for cardiovascular and cerebrovascular events in patients with primary aldosteronism (PA) and normal basal PAC (nPA) than in those with high basal PAC (hPA). However, the differences in therapeutic outcomes between nPA and hPA are unclear. The aim of this multi-institutional, retrospective cohort study was to determine the clinical significance of nPA to therapeutic outcomes, including adrenalectomy (ADX) and treatment with mineralocorticoid receptor antagonists (MRAs). Methods A total of 1146 patients with PA who were diagnosed and underwent adrenal venous sampling (AVS) between January 2006 and October 2016 were enrolled. The clinical parameters at baseline and after ADX or treatment with MRA were compared between the nPA and hPA groups. Results Significantly higher rates of absent clinical success (36.6 vs. 21.9%, P = 0.01) and absent biochemical success (26.4 vs. 5.2%, P < 0.01) were found for the nPA group than for the hPA group, respectively. Logistic regression analysis identified baseline PAC as a significant independent predictor of absent clinical success of ADX and MRAs. Conclusions Plasma aldosterone concentration at baseline was a significant and independent predictor of absent clinical success of ADX and MRA. Mineralocorticoid receptor antagonist treatment appeared to be a better therapeutic choice than ADX in the nPA group.