There are limited data on reference values of left atrial volume indexes (LAVIs) in adults without known cardiovascular disease or risk factors, as well as their stratification by age, gender, and diastolic stage. LAVIs were calculated using the biplane area-length method in accordance with guidelines in 966 consecutive patients (mean age 48.0 ± 15.7 years) with no known cardiovascular disease or risk factors, with preserved left ventricular systolic function and normal or grade I diastolic dysfunction (DD). The mean LAVI was 23 ± 8 ml/m2. Using a conventional cut-off value of 34 ml/m 2 (mean + 2 SDs of the values derived from the guidelines) to define abnormal LAVI would label about 10% of patients as having dilated left atria and structural heart disease, whereas using the American Society of Echocardiography's recommended cutoff of the mean + 1 SD (i.e., 28 ml/m 2) would do so for up to about 20%. The mean LAVI was similar between the genders (p = 0.10) and among different age groups (p = 0.60 for the trend across decades). Finally, when stratified by diastolic function, the mean LAVIs were 23.2 ± 8.3 and 22.2 ± 8.7 ml/m2 for patients with normal (n = 653) and grade I DD (n = 313), respectively (p = 0.10). In conclusion, in this cohort of patients without known cardiovascular disease or risk factors, the cut-off values for abnormal LAVI were greater than those adopted in the guidelines. There was no variation, however, by gender, age, or grade I DD, although subjects with long-standing grade I DD and/or high filling pressures were likely underrepresented.