Background Medical students' attitude towards psychiatry (ATP) and mental illness will impact their choice of psychiatry as a future specialization and the quality of mental healthcare that they deliver to their patients. There is a paucity of longitudinal research on students' ATP and mental illness at different periods during medical school. We aimed to assess the attitudes of a cohort of medical undergraduates towards psychiatry and mental illness, before and after a clinical psychiatry rotation. Methods Medical students, in their second clinical year, underwent the first assessment on the 1st day of the psychiatry rotation. Socio-demographic information was collected. ATP and mental illness were assessed using the ATP-30 and the attitudes towards mental illness (AMI) scale, respectively. Assessments were repeated on the last day of the rotation and again 1 year later. Results One hundred and three medical students completed the pre- and immediate post-rotation survey questionnaire. One student withdrew consent for the 1-year assessment. There was an increase in ATP-30 and AMI scores after the rotation, and this persisted at the 1-year assessment. However, only the increase in ATP-30 scores was statistically significant. There was a significant reduction in the number of students with an overall negative attitude towards psychiatry and mental illness at 1 year. Conclusion Students generally had positive attitudes towards psychiatry and mental illness before the rotation. This improved further by the end of the rotation and persisted at 1 year of follow-up.