Objective       To compare the outcomes of embolization in the treatment of intracranial un-ruptured small aneurysms (diameter ≤5 mm) and medium-large aneurysms.       Methods       Fifty-four patients with intracranial un-ruptured aneurysms admitted in our department from June 2011 to August 2014 were enrolled in this study. According to the diameter of aneurysms

they were divided into small aneurysms group (diameter ≤5 mm

n=16) and medium-large aneurysms group (diameter 5 mm

n=38). All patients received interventional embolization. They were followed up in our clinic or through telephone in 3 months after being discharged

and examined through digital subtraction angiography (DSA) in 6 months after dehospitalization. The rates of embolization

complications and recurrence were compared between the 2 groups.       Results       (1) In the small aneurysms group

16 cases (100%) were completely embolized

and 13 cases (81.3%) were by stent assisted coil

while 36 cases (92.1%) from the medium-large aneurysms group obtained complete embolization

and 24 cases (63.2%) were embolized by stent assisted coil. Complete embolization rate was higher in the small aneurysms group

with no statistical significance compared with the other group (P0.05). (2) Symptomatic cerebral vasospasm was found in 2 cases (12.5%) in the small aneurysms group

and in 5 cases (15.8%) from the medium-large aneurysms group. Intraoperative aneurysm rupture occurred in 1 patient (2.6%) from the medium-large aneurysms group. The incidence of complications was slightly lower in the small aneurysms group

but there was no statistical significance with the other group (P0.05). (3) In the small aneurysms group

14 cases (87.5%) recovered well

and 11 (68.8%) were identified without show of recurrence by DSA. And in the medium-large aneurysms group

30 patients (78.9%) recovered well

however

3 cases (7.9%) was found recurrence among all the 26 cases (68.4%) receiving follow-up DSA. Thus

small aneurysms group showed better prognosis and lower recurrence rate

though with no statistical significance (P0.05).       Conclusion       Interventional embolization treatment has good curative effect for intracranial un-ruptured small and medium-large aneurysms.