BACKGROUND Benign adrenal tumors are commonly discovered on cross-sectional imaging. Mild autonomous cortisol secretion (MACS) is regularly diagnosed, but its effect on cardiometabolic disease in affected persons is ill defined. OBJECTIVE To determine cardiometabolic disease burden and steroid excretion in persons with benign adrenal tumors with and without MACS. DESIGN Cross-sectional study. SETTING 14 endocrine secondary and tertiary care centers (recruitment from 2011 to 2016). PARTICIPANTS 1305 prospectively recruited persons with benign adrenal tumors. MEASUREMENTS Cortisol excess was defined by clinical assessment and the 1-mg overnight dexamethasone-suppression test (serum cortisol: 138 nmol/L and abs...