ABSTRACT Objective: To discuss the value of the three-dimensional speckle tracking imaging in evaluation of the left atrial function in normal adults. Methods: 104 volunteers were divided into adolescence, middle-aged and elderly groups according to age. Acquired full volume cardiac images and applied 3D-STI off-line analysis software to get the time-volume curve of left atrium, then got left atrial maximum volume(LAVmax), left atrial pre-systole volume(LAVpre), left atrial minimum volume(LAVmin) and calculated left atrial total emptying volume(LAVt=LAVmaxi-LAVmin), left atrial total emptying fraction(LATEF=100%×LAVt/LAVmax), left atrial expansion index(EI= 100%×LAVt /LAVmin), left atrial passive emptying volume(LAVp=LAVmaxi-LAVpre), left atrial passive emptying fraction(LAPEF=100%×LAVp/LAVmax), left atrial active emptying volume(LAVa)=LAVprei-LAVmin), left atrial active emptying fraction(LAAEF=100%×LAVa/LAVpre), the passive emptying percentage of total emptying(PE=LAVp/LAVt), active emptying percentage of total emptying(AE=LAVa/LAVt). All the parameters were standardized by BSA. Of the above parameters, LAVmaxi, LAVprei, LAVmini, LAVti, LATEF and EI represent reservoir function; LAVpi, LAPEF and PE represent conduit function; while LAVai, LAAEF and AE represent booster pump function of the left atrum in heart cycle respectively. Results: 1. Reservoir function index: LAVmaxi, LAVprei, LAVmini and LAVti increased with increasing age(P<0.05); there was no significant difference in LATEF and EI among the three groups(P>0.05). 2. Conduct function index: the LAVpi increased in elderly group when compared with the adolescence and middle-aged groups(p<0.05),but there was no significant difference in the later two groups(P>0.05); Compared to the adolescence group, LAPEF and PE decreased in the middle-aged and elderly groups(P<0.05), while there was no statistical difference between the later two groups(P>0.05).3. booster pump function index: From the adolescence to the elderly group, LAVai and LAAEF increased significantly(P<0.05); Compared to the adolescence group, the AE increased in middle-aged and elderly group(P<0.05),while the difference between the later two groups was not significant(P>0.05). Conclusion: Three-dimensional speckle tracking imaging can be used to detect changes of left atrial volume and function in normal adults of different age, providing a reliable means for monitoring the early changes of left atrial function and subclinical cardiovascular disease.