〔Abstract〕 Objective To compare collateral status on single-phase CT angiography(sCTA) and multiphase CT angiography(mCTA) and their ability to predict a target mismatch on CT perfusion(CTP) and clinical outcomes in patients with acute ischemic stroke(AIS). Methods Sixty-eight AIS patients with occlusions in the M1 segment of the middle cerebral artery and/or intracranial internal carotid artery within 24 h onset were included. The collaterals assessment of sCTA and mCTA were compared. The ability to predict target mismatch on CTP and clinical outcomes was compared between sCTA and mCTA by using receiver operating curve analysis. Results mCTA was better for visualizing collaterals when compared with sCTA. The ability of mCTA to predict target mismatch(AUC=0.82;95%CI:0.727,0.877) and clinical outcome(AUC=0.851;95%CI:0.735,0.944) was better than that of sCTA(P<0.05 overall). When it comes to collateral status>2, mSCTA predicted target mismatch on CTP was the best. The ability of mCTA to predict clinical outcome was comparable to CTP(P=0.29). Conclusion mCTA can be a new tool to combine with CTP for the imaging triage of patients with acute ischemic stroke.