Junior doctors are at risk of work-related burnout and mental health problems due to training workload demands and responsibilities. This study investigated the predictors of work-related burnout and depressive symptoms in junior doctors. Participants were 349 Australian doctors in postgraduate years 1-4, who completed a web-based survey assessing emotional labour (surface and deep acting), training stress, work-related burnout, and depressive symptoms. We tested a model in which surface acting and training stress were associated positively with work-related burnout, where deep acting was associated negatively with work-related burnout, where work-related burnout was associated positively with depressive symptoms, and where work-related burnout mediated the relationship between emotional labour, training stress, and depressive symptoms. Surface acting and training stress were associated with work-related burnout and depressive symptoms in the expected directions, deep acting and work-related burnout were associated with depressive symptoms, and work-related burnout fully mediated the relationships between training stress, surface acting and depressive symptoms. The results suggest that assisting junior doctors to manage workload demands and patient contact will have beneficial effects on their work enthusiasm and mental health.