"Cold Blood" was first broadcast in the United Kingdom on BBC One and simulcast on BBC HD on 29 May 2010. Initial overnight ratings showed that the episode was watched by 5.7 million viewers, a million more than the previous week. Final consolidated ratings rose to 7.49 million (7.04 million on BBC One and 0.45 million on BBC HD), ranking the show fourth for the week ending 30 May 2010 on the channel and the highest rated show on BBC One for the day. The episode received an Appreciation Index of 85, considered "excellent".
