Abstract Background The aim of this project was to investigate in members of the Vietnamese community in Melbourne the impact of Mental Health First Aid (MHFA) training on attitudes to people with mental illness and on knowledge about mental disorders. Our hypotheses were that at the end of the training participants would have increased knowledge of mental disorders and their treatments, and decreased negative attitudes towards people with mental disorders. Methods Respondents were 114 participants in two-day MHFA training workshops for the Vietnamese community in Melbourne conducted by two qualified MHFA trainers. Participants completed the research questionnaire prior to the commencement of the training (pre-test) and at its completion (post-test). The questionnaires assessed negative attitudes towards people with mental illness (as described in four vignettes), ability to recognise the mental disorders described in the vignettes, and knowledge about how to assist someone with one of these disorders. Responses to open-ended questions were content analysed and coded. To evaluate the effect of the training, answers to the structured questions and to the coded open-ended questions given at pre- and post-test were compared using McNemar tests for dichotomous values and Wilcoxon tests for other scores. Results Between pre- and post-test there was significant improvement in recognition of mental disorders; more targeted and appropriate mental health first aid responses, and reduction in inappropriate first aid responses; and negative attitudes to the people described in the vignettes declined significantly on many items of the stigma scale. Conclusion A two-day, MHFA training course for general members of the Vietnamese community in Melbourne demonstrated significant reductions in stigmatising attitudes, improved knowledge of mental disorders and improved knowledge about appropriate forms of assistance to give to people in the community with mental disorder. There is sufficient evidence to scale up to a population level program for the Vietnamese community, and a need for longitudinal evaluation of such a scaled up program.