BackgroundMedical education is a multifarious endeavour integrating a range of pedagogies and philosophies. Complexity as a science or theory (‘complexity’) signals a move away from a reductionist paradigm to one which appreciates that interactions in multi-component systems, such as healthcare systems, can result in adaptive and emergent outcomes. This examination of the nexus between medical education and complexity theory aims to discover ways that complexity theory can inform medical education and medical education research.MethodsA structured literature review was conducted to examine the nexus between medical education and complexity; 5 databases were searched using relevant terms. Papers were included if they engaged fully with complexity as a science or theory and were significantly focused on medical education. All types of papers were included, including conceptual papers (e.g. opinion and theoretical discussions), case studies, program evaluations and empirical research. A narrative and thematic synthesis was undertaken to create a deep understanding of the use of complexity in medical education.ResultsEighty-three papers were included; the majority were conceptual papers. The context and theoretical underpinnings of complexity as a relevant theory for medical education were identified. Bibliographic and temporal observations were noted regarding the entry of complexity into medical education. Complexity was relied upon as a theoretical framework for empirical studies covering a variety of elements within medical education including: knowledge and learning theories; curricular, program and faculty development; program evaluation and medical education research; assessment and admissions; professionalism and leadership; and learning for systems, about systems and in systems.DiscussionThere is a call for greater use of theory by medical educators. Complexity within medical education is established, although not widespread. Individualistic cultures of medicine and comfort with reductionist epistemologies challenges its introduction. However, complexity was found to be a useful theory across a range of areas by a limited number of authors and is increasingly used by medical educators and medical education researchers. This review has further conceptualized how complexity is being used to support medical education and medical education research.ConclusionThis literature review can assist in understanding how complexity can be useful in medical educationalists' practice.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12909-023-04471-2.