Rosai-Dorfman disease (RDD), a rare form of histiocytosis, has been reported to cause choroidal masses and subsequent serous retinal detachments. We present a case of RDD associated with a choroidal mass and retinal detachment that did not respond to corticosteroid treatment and regressed after treatment with photodynamic therapy (PDT). Following treatment, the patient had a successful anatomic and clinical outcome, with no recurrence of serous detachment and 20/25 visual acuity. This is the first report of choroidal RDD successfully treated with PDT. [ Ophthalmic Surg Lasers Imaging Retina . 2021;52:568–571.]