INTRODUCTION: Mindfulness-based interventions (MBIs) have gained popularity in medical education. A systematic review was conducted to determine the effectiveness of MBIs for reducing psychological distress in undergraduate medical students. METHODS: A search protocol was conducted using online databases Embase, PubMed, PsycINFO, and MEDLINE. Articles were required to meet the following criteria to be included: (1) describe a MBI or use of mindfulness exercises as part of an intervention, (2) include at least one of: stress, burnout, fatigue, or depression, as an outcome, (3) include quantitative outcomes, and (4) published in English in a peer-reviewed journal. RESULTS: Twelve articles were reviewed. Seven studies reported improvements in at least one targeted outcome. Four of seven studies exploring the impact on stress reported improvements. Five articles studying depression reported reductions. One study exploring burnout reported a decrease on a single subscale. Only one study measured the impact on fatigue (no change reported). Half of studies reviewed included predominantly female samples. CONCLUSIONS: Mixed evidence was found for the use of MBIs for reducing psychological distress in undergraduate medical students. Future work should aim to clarify the impact of mindfulness on burnout and fatigue, and explore the replicability of improvements in male medical students alone.