Abstract PURPOSE: To report a case of Alcaligenes xylosoxidans endophthalmitis and to increase awareness of its potential as an intraocular pathogen. METHODS: An 80-year-old woman in good general health developed A. xylosoxidans endophthalmitis 8 months after an uncomplicated cataract extraction performed at another institution. Eventually, vitrectomy with removal of the intraocular lens and capsule was performed because of recurrent disease after intravitreal antibiotic injections. RESULTS: Microbiologic examination of the vitreous biopsies and capsule disclosed A. xylosoxidans, a motile, gram-negative rod resistant to many antibiotics. CONCLUSION: A. xylosoxidans should be considered as a cause of low-grade endophthalmitis after cataract surgery.