Abstract: Objective To investigate the clinical characteristics of children infected by Streptococcus anginosus group. Methods From January 1, 2012 to December 31, 2019, cases positive for Streptococcus anginosus group in bacterial culture in Beijing Children's Hospital were collected retrospectively. Combined with their microbiology, radiology and clinical data, each isolated strain was evaluated in detail to exclude the positive cases caused by contamination and colonization strains. Age of onset, gender, clinical manifestations, laboratory tests, treatment, outcome and prognosis of the cases were analyzed and the bacterial identification and drug sensitivity test were conducted. According to the medical history, the patients were divided into two groups with or without underlying diseases. Underlying diseases referred to congenital heart disease, pyriform sinus fistula, dermal sinus, congenital esophageal fistula, congenital choledochal cyst and other congenital malformations, immunosuppression, paranasal sinusitis, cerebral palsy, esophageal foreign bodies, etc. Results A total of 119 cases were at the age of 33 days to 16 years, with a median age of 4 years. There were 56 (47.1%) in underlying disease group including 27 (48.2%) with head and neck infection, 11 (19.6%) with central nervous system (CNS) infection and 10 (17.9%) with bloodstream infection (BSI). Of head and neck infection, 70.4% (19/27) was pyriform sinus fistula; of BSI, 60.0% (6/10) was immunodepression; of CNS infection, 63.6% (7/11) was congenital heart disease. There were no significant differences in the average hospitalization days, average fever duration, WBC count, neutrophil percentage, CRP and ESR between the two groups. One hundred and four (93.7%) children infected by Streptococcus anginosus group had abscess with head and neck infection, abdominal infection, CNS infection, BSI accounting for 41.2%, 20.2%, 12.6% and 12.6% respectively. For strain identification, there were 44 cases of Streptococcus anginosus, 41 cases of Streptococcus constellatus and 34 cases of Streptococcus intermedius. The sensitivity to penicillin, ampicillin, cefotaxime, erythromycin, clindamycin and vancomycin was 87.4%, 93.2%, 94.2%, 20.2%, 21.8%, 100% and 100%, respectively. One case died and 2 cases gave up the treatment because of critical illness. Conclusion Streptococcus anginosus group infection could result in abscesses. Head and neck infection was the most common. There were no significant differences in the clinical characteristics of Streptococcus anginosus group infection in children with and without underlying diseases. Streptococcus intermedius was the main cause of brain abscess. Most of Streptococcus anginosus group strains were sensitive to penicillin antibiotics but resistant to macrolides.