Abstract： Objective To explore the normal range of the volume of internal capsules in Chinese adults of the Han nationality and its relationship with age,body habitus,and craniocerebral volume.Methods One thousand healthy volunteers (age range =18 to 80 years) were divided into 5 groups according to their age;Group A ( 18 to 30 years old),group B (31 to 40 years),group C (41 to 50 years),group D (51 to 60 years),and group E (61 to 80 years).Each group consisted of 100 males and 100 females.MR imaging was performed in all of the volunteers using T1 weighted three-dimensional nagnetization prepared rapid acquisition gradient echo sequence. After three dimension data reconstruction,the volumes of bilateral internal capsules were manually measured. The volumes of bilateral internal capsules were compared by paired sample t test.The internal capsule volumes were compared between male and female by independent sample t test,and the differences among 5 age groups were compared by one-way ANOVA.The relationship between the volumes of internal capsule and age,body habitus or cerebral volume were analyzed using bivariate correlation.Results The left and right internal capsule volumes were (2809 ± 393) and (2677 ± 343 ) mm3 respectively.The left internal capsule volumes were significantly larger than that of right (t =12.078,P ＜ 0.05 ).The left and right side of internal capsule volumes in male were (2863 ± 396) and (2744 ±358) mm3 respectively,and (2754 ±385) and (2609 ±314) mm3 in female.The left and right internal capsule volumes were larger in males than in female (t =1.982,2.851 ;P ＜ 0.05 ).The left internal capsule volume of the 5 age groups were ( 3273 ± 361 ),( 2943 ± 299 ),( 2777 ± 255 ),( 2607 ± 199 ),(2444 ±213) mm3,and the right were (2993 ± 361 ),(2814 ± 270),(2682 ± 239),(2543 ± 219),(2351 ±210) mm3.There were significant differences among 5 age groups between left and right internal capsule volume ( F =55.244,34.493 ; P ＜ 0.05 ).There was significant negative correlation between the volume of left and right internal capsule and age ( r =- 0.718,- 0.637 ; P ＜ 0.05 ).Conclusions 1.5 T MR scanner can be used to accurately measure the internal capsule volumes.There is a significant negative correlation between age and internal capsule volumes.