Abstract. The authors describe a case of traumatic retinal dialysis with retinal detachment from a water balloon slingshot during a "water balloon war." A 31year-old woman presented with decreased visual acuity in her right eye 2 days after being hit by a water balloon. The visual acuity in the right eye was counting fingers and fundus examination showed subtotal retinal detachment secondary to a superonasal dialysis. The patient underwent a scleral buckling procedure with external drainage, and at 1 8 months visual acuity was stable at 20/50 with attached retina. Water balloon eye injuries can result in permanent visual loss. More public awareness needs to be created regarding the potential harmful effects of this commonly used "toy." [Ophthalmic Surg Lasers 1998;29:864-865.]