Many survivors of aneurysmal subarachnoid haemorrhage (aSAH) have persistent cognitive deficits. Underlying causes of these deficits have not been elucidated. We aimed to investigate if cerebral perfusion in the acute phase after aSAH measured with CT perfusion (CTP) is associated with cognitive outcome 3 months after aSAH. We included 71 patients admitted to the University Medical Center Utrecht who had CTP performed within 24 h after ictus and neuropsychological examination after 3 months. Perfusion values were measured in predefined regions of interest for cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP). The relationship with global cognitive functioning, as measured with a mean z score of all cognitive tests, was examined by linear regression analyses. Adjustments were made for age, education, method of aneurysm treatment, and presence of non-acute medical complications. TTP was associated with cognitive functioning in the univariable analysis (B = -0.042, 95 % CI -0.076 to -0.008), but not after adjustment for age (B = -0.030, 95 % CI -0.065 to 0.004). For CBF, CBV and MTT no relationship with cognitive functioning was observed. Cerebral perfusion measured with CTP within 24 h after onset of aSAH is not associated with cognitive outcome after 3 months. The lack of an association might be explained by the delay between onset of aSAH and CTP. However, CTP assessment within the first minutes after aSAH is impossible in large series of patients.