Background: Our study was designed to evaluate the efficacy of perfusion computed tomography (PCT) in patients with acute phase of stroke for the early diagnosis of this pathology and prediction of hemorrhagic transformation in the ischemic area. Material and methods: We studied the functional PCT maps obtained at admission from 23 patients with acute ischemic stroke, compared to follow-up computer tomography or magnetic resonance imaging. Results: Mean Transit Time(MTT) map showed that the highest sensitivity (80.3%) and parameters of relative Cerebral Blood Flow (rCBF) and Cerebral Blood Volume (rCBV) were the most specific (95.0% and 96.9%, respectively) in the early diagnosis of ischemic stroke. Automatic technique “Tissue Classification” showed the highest value of the overall accuracy (91.7%), a significant correlation with the final stroke extension and differentiation of potentially salvageable regions from the irreversibly damaged, which plays an important role in the treatment management. Evaluation of permeability function of the blood-brain barrier with a Permeability Surface area product (PS) showed high values of specificity, sensitivity and overall accuracy (89.5%, 75.0% and 87.0%) in the prediction ability of hemorrhagic transformation. Conclusions: Quantitative analysis of functional parameters of dynamic cerebral perfusion computed tomography has significant efficacy in emergency diagnosis of acute ischemic stroke and hemorrhagic transformation prediction in tissue exposed to ischemia.