Time is a key issue for both ergonomists and engineers when they engage in production system interventions. While not their primary purpose, the actions of engineers have major effects on biomechanical exposure; possibly of much greater magnitude than many ergonomics interventions. This paper summarises the aims, actions and tools of engineers and ergonomists, emphasising time-related outcomes. Activities of the two groups when attempting to manipulate time aspects of work may be contradictory; engineers wishing to improve production and ergonomists aiming at better health as well as contributing to production. Consequently, tools developed by ergonomists for assessing time aspects of work describe rest patterns, movement velocities or daily duration of exposures, while engineering tools emphasise time-efficient production. The paper identifies measures that could be used to communicate time-relevant information between engineers and ergonomists. Further cooperation between these two stakeholders as well as research on the topic are needed to enable ergonomists to have a larger impact on the design of production systems.