A meta-analysis of proportions was performed, and age-stratified estimates for each finding were derived from age-adjusted non-linear models. We identified 6536 citations and included 35 reports of 34 studies, comprising 40,777 participants. PubMed/MEDLINE, EMBASE and SCOPUS were searched from inception to May 24, 2021. We performed a systematic review and meta-analysis to determine the prevalence of various incidental findings. As the volume and fidelity of magnetic resonance imaging (MRI) of the brain increase, observation of incidental findings may also increase.