A penguin (Eudyptula minor) from Tasmania, Australia, died following a 3-day illness. The liver and spleen parenchyma contained grossly visible foci of discoloration. Numerous tachyzoites of Toxoplasma gondii were seen associated with necrosis in sections of liver and spleen. The diagnosis was confirmed by immunohistochemical staining of parasites. This apparently is the first report of fatal toxoplasmosis in a penguin.