Objective To explore the diagnosis value of CTA on posterior inferior cerebellar artery ( PICA ) aneurysm.Methods The clinical data of 2 patients with PICA aneurysms were analyzed retrospectively .Results Two patients were elderly,acute onset,CT confirmed subarachnoid hemorrhage ,CTA of the first time were negative within 3 h after the onset .After the treatments of preventing cerebral vasospasm , increasing blood volume , protecting brain cells and etc for 3-7 d, one case improved ,one case were invalid .Given CTA examination again then found 3 aneurysms, one case with 2 aneurysms located on the left side of the PICA , accompanying with hydrocephalus ,and the other case with 1 aneurysm located on the left side of the PICA .Two patients obtained a good image evaluation and rich information .Conclusions In view of the particularity of the PICA aneurysms , CTA can be used as the preferred method of examination , which can provide comprehensive imaging data .When CTA examination of the first time is negative , giving CTA again remains an ideal choice after short-term treatment .