This study examines the impact of career uncertainty on post-PhD researchers' experiences. Drawing on an identity-trajectory approach and a qualitative design, we analysed experiences of post-PhDs from the UK and Switzerland. Our findings show that in the course of their work experiences, career uncertainty takes two different forms: intellectual uncertainty and occupational uncertainty. On a daily basis, both forms strongly impact the participants' work and personal lives and can limit their ability to plan for the future, restrict their developing research expertise and networks and induce tension in trying to reconcile work and personal lives. While often struggling with a blurred institutional status, participants 'hang tough' despite their uncertain situation, notably by clinging to the academic researcher identity. Contributing to the previous work on the increasing casualisation of post-PhD positions and the resulting challenges, our study offers new insights into how different aspects of career uncertainty influence post-PhDs' work and identity.