AIMS: This study aims to establish the prevalence of aspirin, dipyridamole, clopidogrel, and warfarin use in patients undergoing cataract surgery, and to compare local anaesthetic and intraoperative complication rates between users and non-users. METHODS: The Cataract National Dataset was remotely extracted and anonymised on 55,567 operations at 12 NHS Trusts using electronic patient records (EPRs) between 2001 and 2006. RESULTS: This report analyses 48,862 of the 55,567 operations from the eight centres, which routinely recorded a drug history. In all, 28.1% of the 48,862 patients were taking aspirin, 5.1% warfarin, 1.9% clopidogrel, and 1.0% dipyridamole. The recording of any complication of a sharp needle or subtenon's cannula local anaesthetic block was increased in patients taking clopidogrel, 8.0% (P<0.0001) or warfarin, 6.2% (P=0.0026) vs non-users, 4.3%, but no increase in potentially sight-threatening complications was identified. The incidence of subconjunctival haemorrhage was increased in patients taking clopidogrel, 4.4% (P<0.0001) or warfarin, 3.7% (P<0.0001) vs non-users, 1.7%. The recording of any operative complication was increased in those taking clopidogrel, 7.3% (P=0.0002) vs non-users, 4.4%, but the haemorrhagic operative complications of choroidal/suprachoroidal haemorrhage and hyphaema were not significantly increased. The non-haemorrhagic complication of posterior capsular rupture (PCR) was increased in those taking clopidogrel, 3.23% (P=0.0057) vs non-users, 1.77%. CONCLUSIONS: Clopidogrel or warfarin use was associated with a significant increase in minor complications of sharp needle and subtenon's cannula local anaesthesia but was not associated with a significant increase in potentially sight-threatening local anaesthetic or operative haemorrhagic complications.