OBJECTIVE To generate normal reference values for left ventricular mid-diastolic wall thickness (LV-MDWT) measured by using CT angiography. METHODS LV-MDWT was measured in 2383 consecutive patients, without structural heart disease, undergoing prospective electrocardiographically (ECG) triggered mid-diastolic coronary CT angiography. LV-MDWT was manually measured on automatically segmented short-axis images according to the American Heart Association's 17-segment model. Commercially available automatic software was used to calculate the left ventricular (LV) mass. RESULTS Among the 2383 patients, average LV-MDWT was 7.24 mm ± 1.86 (standard deviation [SD]), with the basal anteroseptal segment being the thickest wall (8.71 mm ± 2.19) and the apical inferior segment being the thinnest wall (5.9 mm ± 1.58; P < .001). Over all LV segments, the maximum upper limit, as defined as 2 SD above the mean, was 13.6 mm for men (LV1) and 11.2 mm for women. For men, only the basal anterior segment was above 13 mm. There was a significant difference in average LV-MDWT between women and men with 6.47 mm ± 1.07 and 7.90 mm ± 1.24, respectively (P < .001). Significant differences in LV-MDWT were found in the subgroups aged less than 65 years and greater than or equal to 65 years (P < .001). There was a strong correlation between LV-MDWT and LV mass (P < .001). CONCLUSIONS Normal sex- and age-specific reference ranges for LV-MDWT in prospective ECG-triggered mid-diastolic coronary CT angiography have been provided. These benchmarks may expand the diagnostic and prognostic roles of CT angiography, beyond its role in the identification of coronary artery disease.© RSNA, 2019.