Seventy-one patients from northern Sweden were diagnosed with chronic subdural haematomas (CSDH) and treated at the Department of Neurosurgery at Umeå University Hospital over 12 months. Fifty-four patients with CSDH had a history of head trauma (trauma group), while 17 patients had no previous head trauma (non-trauma group). In the non-trauma group 71% of patients were treated with anticoagulants or antiplatelet aggregation agents (AAA) compared to 18% in the trauma group. Considering only AAA, 59% of the non-trauma patients were treated with these drugs versus 17% of patients in the trauma group. The recurrence rate for all patients was 17%. These findings confirm that the use of anticoagulants and AAA is over-represented in patients with non-traumatic CSDH. In our study, recurrence was not associated with previous use of anticoagulants or AAA.