Purpose: Left ventricular (LV) ejection fraction (EF) is a ubiquitous measurement of systolic function used to define and assess the severity of LV dysfunction, guide management and assess prognosis. However consensus regarding the lower limit of normal EF is lacking. This study explores the distribution of EF to determine normative reference values by gender and ethnicity. Methods: We performed an individual person data meta-analysis of population-based echocardiographic (echo)studies of volunteers. Demographics, clinical history, height, weight, BP, glucose, and echo measurements were collated. In this analysis we studied EF in adults without hypertension, diabetes, renal or cardiovascular disease. The relationship between age and the 5th centile of EF derived from 2D volume estimates (Simpson single or biplane, or area-length methods) was modelled using quantile regression. The predicted value of the 5th centile was considered the lower reference value (LRV) and is presented with a 95% confidence interval. Gender-specific models were created within each ethnic group. Data are reported for people of European (E), Asian (A) and South Asian (SA) descent, aged ≤70yrs. Results: 21317 healthy subjects from 41 studies, 50% men. EF available in: 6398 E, 926 A, 1324 SA. Among E, the LRV for EF at 50yrs was 49% for men and 50% for women. Among A, EF at 50yrs was 56% for men and 57% for women. Among SA men, EF at 50 yrs was 54% which was higher than E but lower than A. Among SA women, EF was the same as A women (57%). There were small but significant increases in the LRV across age in E men and women, and a difference in LRV suggested between genders for SA (table). View this table: LRV (95% CI) of ejection fraction (%) Conclusion: This large study shows that reference values for EF in healthy adults are associated with ethnicity, and among SA may be associated with gender. Ethnicity and gender are important factors to consider when assessing left ventricular systolic function.