There is a perception that patients who develop a chronic subdural haematoma (CSDH), whilst taking warfarin, do less well than those not taking warfarin. This study looks at such patients to determine the truth of this perception. A retrospective analysis of two time periods (1990;1992 and 1995;1997) looking at all patients with CSDH admitted to this neurosurgical unit for treatment, to determine the incidence and to look more closely at those on warfarin. The influence of warfarin on the incidence, severity and outcome has been studied. Between 1990 and 1992, 11.8% of those patients with CSDH were taking warfarin, whilst in 1995‘1997 20% were on warfarin. The overall number of referrals of CSDH increased from 34 to 150 patients during these time periods. There were no differences in age, sex or other medical disorders between the two groups. No adverse events occurred when the warfarin was stopped temporarily for treatment of the CSDH. There was no increase in recurrence rate in those on warfarin, compared with those not on warfarin. This study, whilst demonstrating an increase in the number of referrals of CSDH and patients with CSDH taking warfarin, has not demonstrated an adverse effect of the warfarin on the outcome of treatment for CSDH. The authors suggest recommencing warfarin 3 weeks after surgical evacuation of CSDH in anticoagulated patients.