Objective: Meditation techniques are widely used as therapy and wellbeing practices, but there are growing concerns about its potential for harm. The aim of the present study is to systematically review meditation adverse events (MAEs), investigating its major clinical categories and its prevalence. Method: We searched PubMed, PsycINFO, Scopus, Embase and AMED up to October 2019. Eligible studies included original reports of meditation practices (excluding related physical practices such as Yoga postures) with adult samples across experimental, observational and case studies. We identified a total of 6742 citations, 83 of which met the inclusion criteria for MAEs with a total of 6703 participants who undertook meditation practice. Results: Of the 83 studies analysed, 55 (65%) included reports of at least one type of MAE. The total prevalence of adverse events was 8.3% (95% CI 0.05-0.12), though this varied considerably across types of studies - 3.7% (95% CI 0.02-0.05) for experimental and 33.2% (95% CI 0.25-0.41) for observational studies. The most common AEs were anxiety (33%, 18), depression (27%, 15) and cognitive anomalies (25%, 14); gastrointestinal problems and suicidal behaviours (both 11%, 6) were the least frequent. Conclusion: We found that the occurrence of AEs during or after meditation practices is not uncommon, and may occur in individuals with no previous history of mental health problems. These results are relevant both for practitioners and clinicians, and contribute to a balanced perspective of meditation as a practice that may lead to both positive and negative outcomes.