Unprofessional behaviours between healthcare staff can have negative impacts on patient safety and staff well-being. Unprofessional behaviour is endemic in the healthcare workforce; however, it is not experienced in the same way by all staff. For temporary employees, work is often associated with marginalisation and stigmatisation and findings consistently suggest that temporary workers have poorer psychological health than permanent employees. Internationally, there has been a steady rise in non-standard employment, including temporary and contingent workers. This trend is also pervasive in the global health sector where increased work intensity, staff burnout, persistent vacancies, low retention and the consequent decline in morale and working conditions has resulted in large numbers of staff leaving health services and an increasing reliance on temporary staff. The purpose of this chapter is to examine how temporary employment status contributes to unprofessional behaviours amongst healthcare staff. We draw on findings from a large qualitative study involving 88 participants, including locums, people who worked with locums and staff with governance and recruitment responsibilities for locums. We argue that stigma and deindividualisation, disparity and inequity, locum voice and silence, weakened interpersonal connections and intersectionality and racism contributed to unprofessional behaviours towards locum doctors.