Labour hire workers are one category of a group more generally labelled contingent, temporary, precarious or casual workers. Research shows they are generally at increased risk of occupational injury and illness compared to permanent employees. It is proposed that one of the causal factors is the unique tripartite employment relationship used to engage labour hire. The dynamics and behaviours in this triangular relationship are discussed with reference to the legal and organisational uncertainty that it frequently presents. A model is proposed that suggests the occupational health and safety interdependence between the three parties. The potential occupational health and safety outcomes for the labour hire worker are examined. Apparent gaps in the existing literature are identified, along with future research opportunities.