Objective To explore the application of multislice computed tomographyic ( MSCT) perfusion imaging in the assessment of acute cerebral infarction. Methods 50 patients who initially diagnosed as acute cerebral infarction in 6 hours after their outbreak of infarction were selected. The Siemens semsation 4 MSCT was used to scan the patients and form time versus concentration curve analysis, including the comparision of region cerebral blood flow (CBF) between the necrosis region and the normal region, region cerebral blood volume (CBV), mean transit time ( MTT). Each case had to be examined by computed tomography at least once a week after infarction. Results 50 patients were found having a lower CBF and CBV in their necrosis region compared with the other side(P＜0.05) ,and had a longer MTT in their necrosis region compared with the other side( P ＜0.05) ,45 patients were observed a shrink of the size of the infarction region compared with the perfusion image in first 6 hours when they were reexamined by CT a week later(P ＜0.05) ,which proved the exist of ischemic penumbra area around the infarction center. Conclusion The multislice computed tomographyic perfusion imaging technology could define the infarction region and size at the early stage of acute cerebral infarction. It also provided clues to indicate the exist of a vascular area around the necrosis centre. It could diagnose acute cerebral infarction at hyperacute period and provide image proof for the thrombolysis in early period and treatment in individual manner.