Primary aldosteronism (PA) is the most common type of secondary hypertension occurring in ∼10% of hypertensive patients. Up to 50% of PA is caused by aldosterone-producing adenomas (APA). We recently performed a microarray assay using 21 pairs of zona glomerulosa (ZG) and zona fasciculata (ZF), and 14 paired APAs. This study is to identify the potential biological processes and canonical pathways involved with aldosterone regulation, APA formation, or APA and ZG cell functions.