To examine CTP of the brain in real patient data after reducing tube current down to 80 mAs to decrease radiation dose.CTP was acquired in 60 suspected stroke patients with 80 (n: 30) or 160 (n: 30) mAs. Data were analyzed retrospectively by two independent readers. SNR, perfusion maps and image quality were compared in hypoperfused and non-affected areas.SNR was significantly higher in CTP with 160 mAs compared to 80 mAs (p < 0.001) in non-affected regions, but there was no significant difference in hypoperfused regions. Overall, images with 80 mAs were rated worse than the ones with 160 mAs (3.0 ± 0.7 versus 4.0 ± 0.7), however, still as sufficient to detect proximal vessel occlusions.Tube current of 80 mAs is still sufficient for the detection of perfusion deficits of proximal vessel occlusions.