Cardiac output (CO) monitoring by uncalibrated arterial pressure waveform analysis (APCO) using the FloTrac/Vigileo™ is feasible in patients with intracranial haemorrhage, but the results of validation studies are contradictory. The aim of the present study was to analyse the clinical agreement between the intermittent bolus thermodilution technique (TDCO) and APCO in patients with non-traumatic intracranial haemorrhage.