Objective To investigate the shape and hemodynamic characteristics of the ruptured posterior communicating artery minimal aneurysms. Methods The clinical data of 42 patients with ruptured posterior communicating artery minimal aneurysm (the maximum diameter < 3 mm,11 ruptured aneurysms and 31 unruptured aneurysms)were collected retrospectively. Three-dimensional DSA shapes of the aneurysms were assessed,and the hemodynamic parameters of the aneurysms were calculated according to their computer simulation models. Results (1)The multiple aneurysms were more common in the unruptured group than those in the ruptured group (58. 1% [18/ 31]vs. 9. 1% [1/ 11]). There was significant difference,P = 0. 006 ). (2 )The complex flow pattern was more common in the ruptured group (63. 6%[7 / 11]vs. 6. 5% [2 / 31],P < 0. 01)and also the changed flow pattern (45. 5% [5 / 11]vs. 3. 2% [1 / 31),P = 0. 003). (3)The median aneurysm wall shear stress of the ruptured group was 0. 74 (0. 52,0. 86)and that of the unruptured group was 1. 03(0. 83,3. 64). There was significant difference between the 2 groups (P =0. 008). Conclusion The unruptured minimal aneurysms are common in patients with multiple aneurysms. Active surgical intervention is recommended for the posterior communicating artery minimal aneurysms with low wall shear stress,complex and change flow.