The use of external labour such as temporary agency workers in the general workforcehas increased in recent decades, but comparatively little is known about their impactwithin the aged care workforce. This article analyses quantitative data from a census ofaged care facilities and a large-scale survey of their workforce regarding the use andimpact of temporary agency workers on internal workers. It demonstrates that employ-ing temporary agency workers helps address labour shortages generally and skill short-ages in particular. However, it has a negative impact on the job satisfaction of internalpersonal care workers – a predictor of an increase in intention to leave. In contrast,there was little impact on internal nurse satisfaction. The use of temporary agencyworkers could therefore create a paradox: increasing personal care worker numbersin the short term, but negatively impacting on their retention in the long term. Giventhe need for an expanded and sustainable aged care workforce, this finding has import-ant implications for organisations, policy and unions.