Endophthalmitis resulting from nonsurgical penetrating trauma to the eye is a relatively uncommon infection in the United States. Data are limited, but most recently published series have attributed the highest incidence of infection to gram-positive organisms, in particular Staphylococcus epidermidis. Fungal causes have been reported far less frequently. Bacillus species are being recognized increasingly as major causes of posttraumatic ocular disease, with rates of infection often making them the second most commonly isolated organisms. Bacillus cereus, an especially virulent pathogen, causes a fulminant endophthalmitis characterized by rapid destruction of intravitreal contents and a uniformly poor visual outcome. Certain toxins elaborated by the organism may contribute to its particular virulence. The currently recommended approach to suspected posttraumatic infection involves early use of diagnostic vitrectomy and intraocular culture, use of intravitreal antibiotics, and combination treatment with systemic and periocular antibiotics.