Objective To investigate the changes of left atrial(LA) segmental strains by using threedimension speckle tracking imaging(3D-STI),and to investigate the feasibility of 3D-STI for assessment of LA myocardial strains in healthy adults.Methods A total of 60 healthy subjects were enrolled.Apical fullvolume images were acquired in all subjects and then were analyzed by off-line 3D-STI analysis software.The software divided LA into 16 segments automatically,they were six walls (anterior,anterior-septal,posterior-septal,inferior,anterior-lateral,posterior-lateral) in basal and middle levels,and four walls (anterior,septal,inferior,lateral) in roof level.The peak longitudinal strain (PALS),peak circumferential strain(PACS),peak area strain(PAAS),the time to peak longitudinal strain(TPLS),the time to peak circumferential strain(TPCS) and the time to peak area strain(TPAS) of left atrial by 3D-STI were obtained and compared.Results ①Compared with the four walls in roof level and anterior-lateral,posterior-lateral walls in middle level,PALS of corresponding walls in basal level were significantly increased (P ＜0.05).PALS of posterior-septal,inferior and posterior-lateral walls in middle level were significantly increased than septal,inferior,and lateral walls of roof level (P ＜0.05).PACS and PAAS of all walls in roof level were significantly increased,as compared with that of corresponding walls in middle and basal levels,and the PACS of posterior-septal wall in basal level were lower than that in middle level(P ＜0.05).②There were no significant differences in PALS,PACS,PAAS between different walls within one level(P ＜0.05).③TPLS,TPCS,TPAS of septal wall were significantly lower than that of lateral wall.TPLS of anterior wall,TPCS and TPAS of inferior wall were significantly lower than that of lateral wall(P ＜0.05).Conclusions 3D-STI is a feasible skill to assess LA myocardial strains in healthy subjects.