BACKGROUND: After a first stroke, further vascular events (especially myocardial infarction and recurrent stroke) are common and often fatal. OBJECTIVES: The objective of this review was to assess the effect of prolonged anticoagulant therapy following presumed non-embolic ischaemic stroke or transient ischaemic attack. SEARCH STRATEGY: We searched the Cochrane Stroke Group trials register. We contacted companies marketing anticoagulant agents. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing anticoagulant therapy, for at least one month, with control in people with previous non-embolic presumed ischaemic stroke or transient ischaemic attack. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected trials for inclusion, assessed trial quality and extracted the data. MAIN RESULTS: Nine trials involving 1214 patients were included. The quality of all trials was poor. All pre-dated routine computerised tomography scanning and use of the International Normalised Ratio to monitor anticoagulation. Anticoagulant therapy did not significantly reduce the odds of death or dependency (two trials, odds ratio 0.83, 95% confidence interval 0.52 to 1.34). Death from any cause (odds ratio 0.95, 95% confidence interval 0.72 to 1.23), and death from vascular causes (odds ratio 0.86, 95% confidence interval 0.66 to 1.13) were not significantly different between treatment and control across all nine trials. Anticoagulant therapy did not reduce the risk of recurrent stroke (odds ratio 0.79, 95% confidence interval 0.56 to 1.13). However, fatal intracranial haemorrhage increased (odds ratio 2.54, 95% confidence interval 1.19 to 5.45), as did major extracranial haemorrhage (odds ratio 4.87, 95% confidence interval 2.50 to 9.49). This means anticoagulant therapy caused 11 additional fatal intracranial haemorrhages and 25 additional major extracranial haemorrhages per year for every 1000 patients given anticoagulant therapy. REVIEWER’S CONCLUSIONS: There appears to be no clear benefit from long-term anticoagulant therapy in people with non-embolic presumed ischaemic stroke or transient ischaemic attack. There appears to be a significant bleeding risk associated with anticoagulant therapy.