Objective To observe the clinical features and prognosis of endogenous bacterial endophthalmitis (EBE). Methods Ten eyes of 10 patients diagnosed with unilateral EBE were retrospectively reviewed, including 7 males and 3 females. The mean age was 57.6±10.8 years old. Eight patients were with diabetes and 7 of them were diagnosed over 5 years. There were 3 patients with hepatocirrhosis, 1 patient with hypertension, and 1 patient with coronary disease. Nine cases had infectious diseases, including liver abscess (7 cases), pulmonary infection (3 cases), erysipelas (1 case) and perianal abscess (1 case). Seven cases had fever history. Culture and drug sensitive tests for aerobic bacteria, anaerobic bacteria and fungal were performed for 9 eyes using vitreous samples from the procedures of vitrectomy and/or intravitreal injection. All patients were treated with broad-spectrum antibiotics and adjusted for drug use according to microbiological culture and drug sensitivity test results. After the diagnosis was established, vitrectomy combined with lens removal was performed in 5 hours (3 eyes) and 24 hours (5 eyes); Vitreous tamponade of C3F8 (1 eye) and silicone oil (7 eyes) was used; At the end of the operation, 0.1 ml vancomycin (1 mg) and 0.1 ml ceftazidime (1 mg) were injected into the vitreous cavity. One eye received intravitreal injection of 0.1 ml vancomycin (1 mg) and 0.1 ml ceftazidime (mg), one eye received evisceration. During the follow up period from 6 to 24 months, visual function, slit lamp and fundus examinations were performed at each office visit. Results All patients complained of blurred vision and 5 patients had ocular pain. The visual acuity was no light perception (3 eyes), light perception (5 eyes); hand motion (1 eye) and 0.1 (1 eye). Corneal edema was found in all 10 eyes; hypopyon in 8 eyes; diffuse vitreous opacity in 10 eyes, including 3 eyes with retinal detachment. For 8 eyes treated by vitrectomy and intravitreal injection, 1 eye was eviscerated due to uncontrolled inflammation. The eye treated with intravitreal injection was enucleated for its uncontrolled inflammation. For 9 eyes received vitreous culture and drug testing, 8 eyes (88.9％) had positive results, including 5 eyes with Klebsiellar pneumonia, and 1 eye with Staphylococcus aureus, or Streptococcus agalactiae or Enterococcus faecalis respectively. At last office visit, 2 eyes were with no light perception; 4 eyes were with hand motion; and 1 eye with visual acuity of 0.1. Conclusions Most of the patients with endogenous bacterial endophthalmitis have systemic predisposing factors. Klebsiella pneumoniae is the leading cause of ocular EBE. Vitrectomy combined with intravitreal injection of antibiotics showed efficacy in treating EBE.