Background Medically unexplained symptoms (MUS) are common in primary health care. Both patients and doctors are burdened with the symptoms that negatively affect patients' quality of life. General practitioners (GPs) often face difficulties when giving patients legitimate and convincing explanations for their symptoms. This explanation is important for reassuring patients and for maintaining a good doctor-patient communication and relationship.Objective To provide an overview of explanatory models for MUS.Study design We performed a systematic search of reviews in PsycINFO and PubMed about explanatory models of MUS. We performed a qualitative analysis of the data according to the principles of constant comparative analysis to identify specific explanatory models.Results We distinguished nine specific explanatory models of MUS in the literature: somatosensory amplification, sensitisation, sensitivity, immune system sensitisation, endocrine dysregulation, signal filter model, illness behaviour model, autonomous nervous system dysfunction and abnormal proprioception. The nine different explanatory models focus on different domains, including somatic causes, perception, illness behaviour and predisposition. We also found one meta-model, which incorporates these four domains: the cognitive behavioural therapy model.Conclusion Although GPs often face difficulties when providing explanations to patients with MUS, there are multiple explanatory models in the scientific literature that may be of use in daily medical practice.