Background Endophthalmitis can be a devastating complication after pars plana vitrectomy. The incidence of post-vitrectomy endophthalmitis is significantly lower than that of endophthalmitis occurring after other intraocular operations. However, normal post-operative pain and inflammation may mask endophthalmitis and lead to delayed diagnosis and grave visual consequences. This study aimed to summarize the outcomes of cases that underwent pars plana vitrectomy over a 10-year period and to analyze the characteristics of post-vitrectomy endophthalmitis. Methods A retrospective observational case study was conducted on all the cases who underwent pars plana vitrectomy in the Beijing Tongren Hospital between January 1, 2002 and March 31, 2012. All cases of endophthalmitis that occurred during a period of 10 years and 3 months were reviewed, and the possible risk factors, clinical findings, causative organism(s), and the sources of infection were analyzed. Results Within the 10-year observational period, 14 patients developed endophthalmitis after pars plana vitrectomy. The incidence of post-vitrectomy endophthalmitis (0.05%) was lower than that reported previously from the same center (0.12%). Staphylococcus epidermidis (five patients, 35.71%) was the most common organism identified in aqueous or vitreous cultures. Eight patients (57.14%) had diabetes mellitus. There was no statistically significant difference (P >0.05) in the incidence of endophthalmitis between period 1 (with antibiotic pretreatment) and period 2 (without antibiotic pretreatment). Surgical procedures for the treatment of endophthalmitis were performed in 10 patients (71.43%). Conclusions This series of cases showed that the incidence of endophthalmitis after pars plana vitrectomy is lower than what was previously reported in our hospital. A variable degree of corneal edema with relatively normal or mildly increased intraocular pressure was one of the commonly observed characteristics of post-vitrectomy endophthalmitis. Staph. epidermidis was the most common causative organism, and antibiotic pretreatment did not lower the incidence of post-vitrectomy endophthalmitis.