Although it is rare, infectious endophthalmitis is a severe ocular complication resulting from intravitreal injection of triamcinolone acetonide (TA). Therefore, care must be taken by ophthalmologists to differentiate between what is infectious and noninfectious endophthalmitis. We report on a 62-year-old woman who received an intravitreal injection of TA for treatment of central retinal vein occlusion. One day after the injection, a hypopion (a white-yellowish deposit) was noted in the inferior anterior chamber. The patient complained that her vision had deteriorated, but there was no pain, eyelid edema, increased conjunctival injection or corneal edema. The hypopion gradually diminished and by the fifth postoperative day, resolved completely without the administration of intravitreal or systemic antibiotic therapy.