Yes / Safe and successful surgery depends on effective teamwork between professional groups, each playing their part in a complex division of labour. This article reports the first empirical examination of how introduction of robot-assisted surgery changes the division of labour within surgical teams and impacts teamwork and patient safety. Data collection and analysis was informed by realist principles. Interviews were conducted with surgical teams across nine UK hospitals and, in a multi-site case study across four hospitals, data were collected using a range of methods, including ethnographic observation, video recording and semi-structured interviews. Our findings reveal that as the robot enables the surgeon to do more, the surgical assistant's role becomes less clearly defined. Robot-assisted surgery also introduces new tasks for the surgical assistant and scrub practitioner, in terms of communicating information to the surgeon. However, the use of robot-assisted surgery does not redistribute work in a uniform way; contextual factors of individual experience and team relationships shape changes to the division of labour. For instance, in some situations, scrub practitioners take on the role of supporting inexperienced surgical assistants. These changes in the division of labour do not persist when team members return to operations that are not robot-assisted. This study contributes to wider literature on divisions of labour in healthcare and how this is impacted by the introduction of new technologies. In particular, we emphasise the need to pay attention to often neglected micro-level contextual factors. This can highlight behaviours that can be promoted to benefit patient care.