||This study focuses on working environment and experiences of PhD candidates at a Dutch university. 250 PhD candidates responded to an online questionnaire and twelve of them were also interviewed. The results of the questionnaire reveal that 38% of the PhD candidates surveyed are at risk of serious mental health problems. This applies in particular to young and international PhD candidates. Having an employment contract has no influence on mental well-being. The more integrated within the university structure, especially in the case of young PhD candidates, and therefore also the more dependent on the academic system, the greater the likelihood of mental health problems, particularly if it is not clear what requirements need to be met or if there seems to be little prospect of an academic career. In such situations, PhD candidates can feel incompetent if they are not offered sufficient support and supervision. It is often unclear whether they have achieved the required standard. At the same time, PhD candidates made positive comments in the interviews about the chance to conduct research and the opportunity to complete a PhD; it is generally a carefully-considered choice. This calls on the University as employer, and the supervisors as those directly supervising the process, to ensure that they make sufficient effort and engage in an open dialogue in order to enable PhD trajectories to be successfully completed. No one denies that conducting PhD research is a stressful period. The workload is felt to be considerable, as clearly also emerges in the interviews with PhD candidates. But this kind of pressure is not a significant predictor of mental health problems among PhD candidates. They are fully aware that the amount of work they need to do is considerable and that this will be at the expense of their work-life balance, at least temporarily. Many PhD candidates take very little time off; holidays are short and work often continues into the evenings and weekends. However, when PhD candidates encounter real problems in dealing with the amount and pace of work, mental health problems can arise. The interviews reveal that this may be associated with teaching duties that take up time that is not offset in other ways. Autonomy at work, often seen as a mitigating factor for stress, does not have that effect for PhD candidates. This may be because PhD candidates always consider their PhD trajectory to be a generally autonomous process for which they are themselves responsible. In this study, the same approach was used as the Belgian research institute ECOOM who conducted in 2016 research into the link between the academic working environment and the (mental) well-being of PhD candidates at Flemish universities. The findings in Flanders would suggest a problem of similar magnitude, albeit with different predictive factors than at Leiden University.