Purpose: To describe a rare case of late reactivation of retinopathy of prematurity (ROP) in a treatment-naive adult female patient. Methods: Clinical examination and multimodal imaging techniques were used to diagnose the patient and guide the treatment, and genetic saliva testing was performed. Results: We describe a 30-year-old female patient who presented with late reactivation of treatment-naive ROP. She was born prematurely and never received a diagnosis of ROP. She presented at the age of 30 years with new onset of flashes and floaters. Fundoscopic examination was consistent with a diagnosis of ROP, with peripheral avascularity evident in the temporal retina bilaterally, a temporal ridge in the right eye, and focal leakage seen bilaterally on fluorescein angiography. The patient was treated with panretinal photocoagulation laser therapy. Genetic testing demonstrated a heterozygous mutation in ZNF408. Conclusions: Retinopathy associated with prematurity may reactivate in adulthood. This late reactivation may be influenced by a history of untreated ROP or by mutations associated with familial exudative vitreoretinopathy.