Objective To investigate the etiological factors of endophthalmitis and evaluate the outcomes of vitrectomy for endophthalmitis.Methods From January 1999 to December 2001, 53 consecutive patients (54 eyes ), 38 men and 15 women, diagnosed as endophthalmitis were retrospectively evaluated. The patients′ ages ranged from 1 year to 74 years (mean 32 years). Two patients (2 eyes) with mild inflammation received antibiotic medication therapy, 5 patients (5 eyes) with no light perception and severe inflammation underwent evisceration, and the other 46 patients (47 eyes) underwent pars plana vitrectomy. Postoperative follow-up ranged from 2 to 32 months (mean 10.5 months). Results Endophthalmitis was diagnosed as resulting from penetrating injury in 32 eyes (59.26%), endogenous endophthalmitis in 8 eyes (14.81%), cataract surgery in 7 eyes (12.96%), gl au coma surgery in 2 eyes (3.70%), vitrectomy in 3 eyes (5.56%), radial keratotomy in 1 eye (1.85%), and unknown reason in 1 eye (1.85%). The postoperative visual a cuities (VA) of these patients increased significantly (P=0.003). The VA of the patients underwent vitrectomy in 3 days was obviously better than those after 3 days (P=0.014), and the VA of the patients underwent vitrectomy in 7 days was obviously beter than those after 7 days (P=0.021). Thirty-seven eyes (68.52 %) had functional success (VA≥0.02), 47 eyes (87.04%) had anatomical success (VAlt;0.02) , and 27 eyes (50.00%) were out of blindness (VA≥0.05). Conclusions Penetrating ocular injury, especially with retained intraocular foreign bodies, is the most common cause of suppurative endophthalmitis. Vitrectomy is a good method for the treatment of endophthalmitis. (Chin J Ocul Fundus Dis，2003，19：93-95)