BACKGROUND: There is research evidence regarding the presence of stigmatising attitudes in psychiatrists towards people with mental illness, but a lack of studies and interventions focused on this issue in low and middle-income countries. AIMS: To assess the feasibility of implementing an anti-stigma intervention for Mexican psychiatric trainees, and its potential effects. METHODS: This study comprised a pre-post design with outcome measures compared between baseline and 3-month follow-up. Quantitative outcome measures were used to evaluate the potential effects of the intervention, whilst the process evaluation required the collection and analysis of both quantitative and qualitative data. RESULTS: Twenty-nine trainees (25% of those invited) participated in the intervention, of whom 18 also participated in the follow-up assessment. Outcome measures showed the intervention had moderately large effects on reducing stereotypes and the influence of other co-workers on trainees' own attitudes. The main mechanisms of impact identified were recognition of negative attitudes in oneself and colleagues, self-reflection about the impact of stigma, one's own negative attitudes and recognition of one's ability to make change. Participants accepted and were satisfied with the intervention, which many considered should be part of their routine training. However, trainees' work overload and lack of support from the host organisation were identified as barriers to implement the intervention. CONCLUSIONS: A brief anti-stigma intervention for Mexican psychiatric trainees is feasible, potentially effective, well accepted and was considered necessary by participants. This study also suggests mechanisms of impact and mediators should be considered for developing further interventions, contributing to reducing the damaging effects that mental health-related stigma has on people's lives.