Hyperacute stroke units were established in London as part of a reorganisation of stroke services in the latter part of the last decade, allowing rapid access to stroke specialist services for patients who could potentially benefit from IV thrombolysis. We audited admission rates and case mix within a London hyperacute stroke unit over the course of approximately 15 months. Admission rates increased linearly over the time period studied. It appears that thrombolysis call rates did not contribute significantly to this increase. Case mix changes were assessed by studying discharge summaries from 2 months 1 year apart (October 2010 and October 2011). There was a significant change in patient gender between the 2 months with a male bias in 2010 and a female bias in 2011 (p<0.05 by χ2test). The total number of patients diagnosed with a TIA, infarct or intracerebral haemorrhage was very similar between the 2 months (127 and 128). However, the number of patients with a non-stroke diagnosis at discharge increased significantly (46 to 76). Common stroke mimics included migraine (15%), functional (12%), seizures (9%), cardiac/autonomic causes (7%), infection (6%) and Bell's palsy (5%). These data have implications for the provision of acute general neurological services as well as stroke services in the UK.