Context The prevalence of depressive symptoms among medical students has been found to be higher than among other students because of their longer studying time, higher workload and larger financial burden. Despite the availability of reviews examining this, some have focused solely on one country, whereas others used databases containing papers of solely one language; therefore, the results from reviews might not be comprehensive. Against this background, this overview aims to synthesise the results from all the published systematic reviews of depression among medical students, in order to provide a more accurate result. Methods A systematic search was conducted of online databases for published systematic reviews or meta-analyses examining the prevalence of depressive symptoms among medical students. The findings of individual studies included in these reviews were extracted and then combined with a random-effects model. Subgroup analysis was conducted by regions. Results A total of 10 studies were selected in this overview, involving 249 primary studies and 162 450 medical students. MEDLINE was the most popular database used in these studies. The overlapping of primary studies in these reviews was appreciably high, except for three studies that focused on specific countries. The overall pooled prevalence was 27.0% (95% CI, 24.7-29.5%). Significant subgroup differences were detected (p < 0.001). The pooled prevalence among studies in the Western Pacific Region was the lowest, 18.9% (95% CI, 11.7-29.0%), whereas that in Africa (40.9%) was the highest (95% CI, 28.8-54.4%). The top five significant factors associated with depressive symptoms were: (i) year of study; (ii) gender; (iii) personal issues; (iv) family relations or issues, and (v) health status. Conclusions Depression affected around a quarter of medical students in general and 40.9% of students in Africa. It is suggested that medical schools and health authorities should introduce preventive measures to curb the high prevalence of depressive symptoms.