Context: Computed tomographic angiography (CTA) is widely applied in the evaluation of cerebral vessels. Contrast enhancement in cerebral CTA without care or test bolus is not always sufficient for high-quality images. Alms: Evaluation of the possibilities of calculation of scan delay for cerebral CTA in case of subarachnoid hemorrhage (SAH), based on clinical data of a patient and to find out prognostic error of the model. Settings and Design: Prospective study in Neurosurgery and Radiology departments. Materials and Methods: Scan delay in 53 patients suffering an acute SAH was measured employing test bolus technique. Cerebral CTA was performed afterwards. Statistical Analysis Used: SPSS for Windows v. 10.1 software package was applied for dispersion analysis, including one-sample Kolmogorov-Smimov's test and Levene's Test of Equality of Error Variances. Results: A statistical model for the prediction of scan delay in SAH was developed. Cerebral CTA scan delay was dependent upon age, neurological status and impact of the latter factors together (P < 0.05). The determined mean square error of prognosis of scan delay of the developed model equals 3.3 sec. Conclusion: Using our proposed model it is possible to estimate an optimal delay time for CTA in most patients with SAH with a determined error.