Many hospitals are still setting up acute stroke thrombolysis services, often delayed by fears over workload. However, there are few data on how many patients require urgent assessment before one is treated. We prospectively studied all referrals to the 24-hour stroke thrombolysis service, February 2009 - January 2010, in Southampton General Hospital. 128 patients were referred to the thrombolysis team and 20 received thrombolysis. The most common reasons for treatment exclusion were: stroke severity (37%), time from onset (26%) or CT findings (15%). Approximately six patients required urgent assessment by the thrombolysis team for every one treated. These data are crucial to inform service planning.