In patients presenting with acute stroke or transient ischaemic attacks (TIA), von Willebrand factor related parameters, including VWF antigen, activity, FVIII:c and propeptides, ADAMTS13 levels and VWF multimers in cases where ADAMTS 13 was reduced will be measured. Global haemostasis will be assessed using thrombin generation and the relation between increase thrombin generation and VWF explored. Thrombin generation will be performed pre and post filtration for the presence of procoagulant microparticles. These parameters will be investigated acutely, at presentation and in convalescence; in addition, the effect on these parameters of treatment such as thrombolysis may be informative. Correlation between measured parameters and adverse clinical outcome would be used to identify markers of severity and progression of ischaemic stroke and identification of potential novel approaches to therapy that might improve outcome.

Inclusion Criteria:

• Patients aged >18 years of age presenting within 9 hours of onset of symptoms will be recruited from the hyperacute stroke unit at UCLH.
• Patients in whom stroke has been excluded or in whom intracerebral haemorrhage has been diagnosed are to be included as 'controls'. The definitive diagnosis will not be immediately obvious at presentation.
• Written consent will be obtained from patients or their nearest relative, particularly in patients with aphasia/dysphasia.

Exclusion Criteria:

• Patients <18 years old
• Patients with systemic vasculitis or active malignancy will be excluded.
• Patients not wishing to participate

all acute admissions presenting with ? stroke