Metastatic lesions in the mouth can resemble common inflammatory lesions. Therefore, we set out to investigate oral metastases whose clinical and imaging characteristics mimicked those of harmless lesions, confusing and delaying the diagnosis. For this, a systematic review was carried out from case reports, case series, and cross-sectional studies in the PubMed/Medline, Scopus, Embase-via Elsevier, Virtual Health Library, Web of Science, and gray literature, using PICO strategy without period restriction. We assessed the quality of studies using the Joanna Briggs Institute assessment tool. A narrative synthesis of the data was carried out. Association analyses using chi-square and Fisher's exact tests were performed, with statistical significance at p<0.05. Most of the lesions came from the lung, breast, kidneys, liver, and thyroid. They affected mainly the mandibles of men, between the fifth and seventh decades of life, causing osteolysis. In soft tissue, there were firm swellings, associated with bleeding. Limitations regarding the heterogeneity of the included studies and the absence of clinic pathological descriptions of the tumors substantially reduced the chance of statistical analysis of the data. Knowing the different possibilities of clinical presentation of oral and maxillofacial metastases is important for the diagnostic suspicion to occur and diagnostic errors to be avoided. Thus, treatment is instituted and survival can be extended. Protocol registration: PROSPERO CRD42020200696