A case of cystoid macular edema related to retinitis pigmentosa treated with intravitreal injection of triamcinolone acetonide is described. A 30-year-old white man with retinitis pigmentosa and progressive visual loss presented with a best-corrected visual acuity of 20/40 in the right eye and 20/80 in the left eye. Examination revealed cystoid macular edema in both eyes. After failure of treatment with oral acetazolamide, intravitreal injection of 0.1 mL of triamcinolone acetonide 0.4% solution was performed in both eyes. In the left eye, macular edema resorbed and visual acuity improved to 20/50. However, 6 months after injection, visual acuity worsened because of recurrence of cystoid macular edema. In the right eye, cystoid macular edema also resorbed, but visual acuity was unchanged. Intravitreal triamcinolone acetonide may be useful for selected cases of cystoid macular edema related to retinitis pigmentosa.