Persistent subretinal fluid (SRF) may occur even after successful surgery for rhegmatogenous retinal detachment (RRD). In most cases, persistent SRF resolves spontaneously within a year, but persistent SRF may cause poor central vision, photoreceptor damage, and the irreversible loss of visual function. Therefore, a variety of interventions have been developed to manage persistent SRF, including the prophylactic use of steroids. As far as we know, an intravitreal steroid injection has never been used in the treatment of persistent SR. This report is a description of steroid treatment used in the case of a 46-year-old male patient with SRF persisting for 15 months after pars plana vitrectomy surgery for the treatment of macula-off RRD. A single-dose intravitreal triamcinolone acetonide (IVTA) injection (4 mg/0.1 mL) was administered; however, no improvement was seen in the lesions. It was concluded that an IVTA injection should be used in a limited fashion in patients with persistent SRF.