Cataract extraction with placement of intraocular lenses is the most common intraocular procedure done today, with endophthalmitis as its most devastating complication. To our knowledge, this is only the third reported case of postoperative endophthalmitis caused by the gram-negative bacillus, Enterobacter cloacae. The course of infection, the treatment, and the laboratory identification of this organism are presented. It is important to add this proven case of gram-negative endophthalmitis to our growing knowledge of causes of this disease because, despite aggressive treatment with vitrectomy and intravitreal antibiotics, the infection was so virulent that it led to eventual phthisis bulbi.