Surgical drape

A surgical robot drape for enveloping a joint of a surgical robot configured to permit axial rotation of a part of a robot arm adjacent the joint about a joint axis. The drape comprising proximal and distal drape material portions configured to provide a sterile barrier over and rotationally fast with a part of the robot proximal or distal of the joint respectively. The drape being configured such that the proximal and distal drape material portions are freely rotatable relative to one another about the joint axis. The proximal and distal drape material portions may comprise a coupling arrangement such as a snap-fit engagement. The proximal and distal drape material portions may comprise a collar and collar shroud.A surgical robot arm for providing a sterile barrier around a surgical robot arm comprising a joint is also included. The drape comprises a sheet configured to form an enclosure having first and third regions spaced apart by a second region. The second region may comprise a material or configuration having a lower effective modulus that the first and third regions. Surgical robot systems are also provided comprising a robot arm and either of the drapes.