| Casualty | |
|---|---|
| Series 21 | |
| No. of episodes | 48 |
| Release | |
| Original network | BBC One |
| Original release | 23 September 2006 – 4 August 2007 |
| Series chronology | |
The twenty-first series of the British medical drama television series Casualty commenced airing in the United Kingdom on BBC One on 23 September 2006 and finished on 4 August 2007. This saw an increase in episodes to 48.