Recurring reports indicate that doctoral and postdoctoral students are regularly confronted with tasks that exceed contractually agreed duties and responsibilities. Research shows that such unreasonable tasks are dysfunctional to both the individual and the organization. However, there is a lack of reliable knowledge about more complex interconnections between unreasonable tasks and their consequences. The paper therefore investigates the mechanisms by which unreasonable tasks relate to doctoral and postdoctoral students' experience of their working conditions. The research model is tested using structural equation modelling (SEM) and data from 1053 doctoral and postdoctoral students at randomly selected German universities. The results reveal that unreasonable tasks have extensive and diverse negative effects on quantitative role overload, effort-reward imbalance, exhaustion, and intention to leave academia. In this way, the paper demonstrates how unreasonable tasks trigger sequences of negative effects that lead to the (post)doctoral students' intention to leave academia. The occurrence of unreasonable tasks is thus problematic not only for the individual, but also for the university as an organization.