Thirty-seven New Zealand Red rabbits were either dosed with methyiprednisolone sodium succinate (MP, n18) about 20 nun before laser irradiafion, or they were left untreated (n=19). Dosing with MP was tapered at 30, 30, 20, 20, and 10 mg/kg/day for five consecutive days. Retinas were irradiated with a multi-lime argon laser to produce retinal injuries (grid of 16 lesions/eye) near hemorrhaging levels (285 mW/lOmsec, 290 ?m retinal spot size). A variety of funduscopic and histologic assessments were made for hemorrhagic and non-hemorrhagic lesions from 10 miii to 6 mo after injury. Fluorescein angiography showed that non-hemorrhagic control lesions stopped leaking at 3d post injury, but MPtreated lesions leaked for 2-4 days longer. After MP treatment, funduscopic lesion areas were similar to controls during the first 24 h then became smaller by 1 mo. After 1 mo, MP-treated lesions increased in area while controls became reduced. Histologic analysis showed no effect on reduction of neutrophils (PMN) in MP-treated lesions over controls at 3 hr. At 24 hi, retinal PMN values in hemorrhagic lesions ofthe MP group were elevated (p<0.05) while monocyte/macrophage counts were reduced (p<0.05) compared to control. At 4d, MP impeded replacement oflost retinal tissue, and contributed to retinal hole development at 1 mo followed by extensive enhancement of chorio-retinal scarring at 6 mo. In severe laser-induced retinal trauma, the immunosuppressive effects of high dose MP therapy contributed to a variety of untoward wound healing outcomes, thereby suggesting caution in its use to treat similar injuries in humans.