AIMS: Multisystemic inflammatory syndrome in children (MIS-C) is a condition noted in some children asymptomatic but positive to Sars-cov-2 antibody and it presents clinical and laboratory changes similar to Kawasaki disease (KD). Oral changes have also been observed. This systematic review evaluated oral manifestations detected in children with MIS-C and KD associated to COVID-19. METHODS AND RESULTS: This work was registered at PROSPERO (#CRD42020225909), following PRISMA guidelines. A comprehensive research was conducted in MEDLINE, Web of Science, EMBASE, LILACS, Scopus, and Grey Literature through August 2021, based on original research evaluating children diagnosed with MIS-C or KD related to COVID-19. Two authors independently screened all retrieved references. Twenty five selected studies evaluated 624 children, mean age 8.78 years. The assessment of the risk of bias (ROB) showed that most of them presented low ROB. Oral manifestations were erythematous mucous membrane, oral ulcers lesions, dry, swollen and cracked lips, and strawberry tongue. CONCLUSION: MIS-C and KD share the same oral manifestations and their identification may lead to an early diagnosis.