In Vietnam, livestock farming policy is designed to develop milk production to increase the country's dairy self-sufficiency. However, workload is one of the main constraints limiting the potential for increasing production and herd sizes on family-run farms. The aim of this paper was to explore the relationships connecting work organisation forms and durations to herd sizes in order to understand the impacts of rationalising work by increasing herd numbers. A work organisation survey was carried on 19 dairy farmers in two regions of northern Vietnam. Statistical analysis was run to identify relationships between herd size, work organisation forms and work durations. A cluster analysis was used to establish a typology. The results show that the volume of routine work is higher in large herds but is also more efficient. Farmers running large herds lighten their family workload by mechanising routine tasks and by employing permanent contract workers. The paper concludes on a set of guidance strategies to help dairy farms develop their activity, such as hiring farm labour and mechanising farm tasks.