Purpose: To describe the clinical course and incidence of culture-proven Postvitrectomy endophthalmitis in 18 patients from five academic centers and three private practices. Methods: Patients undergoing pars plana vitrectomy for recent trauma or endophthalmitis were excluded. The average age was 58 years (range, 21–85 year). Sixty-one percent of the patients (11/18) had diabetes mellitus. The indication for initial vitrectomy was vitreous hemorrhage (n = 10), macular epiretinal membrane (n = 3), recurrent retinal detachment with proliferative vitreoretinopathy (n = 2), retinal detachment with retinoschisis (n =1), proliferative diabetic retinopathy with tractional retinal detachment (n =1), and dislocated intraocular lens (n =1). None of these eyes received prophylactic intraocular antibiotics during the vitrectomy. Results: All eyes were treated with intraocular antibiotics after the diagnosis of Postvitrectomy endophthalmitis was made. Final visual acuity ranged from 20/20 to no light perception and included five eyes with 20/50 or better visual acuity and 11 eyes with less than 5/200 visual acuity. Nine eyes had a final visual acuity of no light perception. Of the 16 eyes infected with a single organism, 71 % (5J7) of eyes infected with coagulasenegative staphylococci retained 20/50 or better final visual acuity compared with no eyes (0/9) infected with other organisms ( P = 0.005). Two eyes infected with both coagulase-negative Staphylococcus and Streptococcus had a final visual acuity of 20/ 400. Three eyes with a total hypopyon later had enucleation or evisceration. Based on the data from four medical centers, the incidence of endophthalmitis after pars plana vitrectomy performed over the last 10 years was 9/12,216 (0.07%). Conclusion: Endophthalmitis after vitrectomy is rare. Postvitrectomy bacterial endophthalmitis caused by organisms other than coagulase-negative staphylococci has a poor visual prognosis.