Purpose: Intravitreal Triamcinolone Acetonide (IVTA) is a useful treatment option for various intraocular diseases such as Macular Edema (ME). The treatment can cause several complications, including transient elevation of intraocular pressure and cataract formation. Here, we describe an atypical complication of IVTA. Case: A 60-year-old Japanese man presented with ME associated with central retinal vein occlusion. We performed intravitreal injection of 4 mg of TA. However, the drug spread behind the posterior lens capsule and also flowed into the anterior chamber. Although the amount of TA particles behind the lens capsule decreased over time, these particles persisted for more than 2 months. Conclusion: Although IVTA is an easy and effective treatment for ME, TA is harmful when injected into inappropriate regions of the eye. Accurate IVTA injection is important for effective treatment.