Viridans group streptococci (VGS) are a heterogeneous group of saprophytic facultative anaerobic bacteria that are part of the normal flora of the oral cavity. The increased resistance to multiple antibiotics in this group of bacteria becomes important in prolonged antibiotic therapies inpatient where these common microorganisms are replaced by multi-resistant bacteria. Objectives: To determine the percentage of VGS strains isolated from oral cavity resistant to antibiotics used in hospital infectious diseases. Material and Methods: This is a descriptive cross-sectional study that included 60 hospitalized patients with a history of antibiotic therapy for more than 3 weeks. The samples were processed following standardized protocols for collection, isolation and identification of oral cavity VGS and a protocol of antibiotic susceptibility testing. The results are shown in tables and graph...