Subdural haematomas (SDHs), and in particular chronic subdural haematomas (CSDHs), are commonly encountered in a neurosurgical practice. The aetiology, presentation, management and prognosis of these are well documented but there are few publications that report on their side prevalence (laterality). We report an analysis of all patients (both operated on and conservatively managed) who presented to the Neurosurgical Service at Christchurch Hospital with SDHs between 1 January 1996 and 30 June 2006. A total of 413 patients presented with a total of 450 SDHs, of which 150 (33.3%) were acute, 38 were (8.4%) subacute and 262 (58.2%) were chronic. The patients ranged in age from 3 months to 95 years. The mean (+/-standard deviation, SD) age of patients with acute SDH was 50.9+/-25.8 years, 65.4+/-19.8 years for subacute SDH and 68.9+/-19.7 years for chronic SDH. A total of 275 (67%) patients were male and 138 (33%) female, with the male predominance occurring in all subgroups. The SDHs were distributed unilaterally in the acute and subacute groups; however, CSDHs occurred more frequently on the left side (57.2% compared to 42.7% on the right; p=0.0345). We discuss the likely reasons behind the increased rate of CSDHs diagnoses on the left side.