Purpose: To report a case of cytomegalovirus retinitis (CMVR) with hypopyon and intense ocular inflammation. Case report: An 81-year-old female was referred to our hospital with a suspicion of postoperative endophthalmitis in the left eye. She had been treated with etoposide and prednisolone for non-Hodgkin's lymphoma. Examination revealed mutton-fat keratic precipitates and numerous infiltrating cells in the anterior chamber with hypopyon. The fundus was invisible due to intense vitreous opacity. Systemic and topical administration of antibiotics was started, and vitrectomy was performed. However, the ocular symptoms did not respond to treatment. Vitrectomy was repeated twice, but severe endophthalmitis findings recurred soon after surgery. Finally, a comprehensive viral PCR test using the intraocular fluid detected CMV with 3.34 x 10(9) copies/ml, leading to a diagnosis of CMV retinitis. Conclusions: If the causative agent is not identified in endophthalmitis that develops in immunosuppressive patients, CMV may also be considered as the possible cause.