The Manchineel tree is an evergreen widely distributed in tropical regions. The toxic nature of Manchineel has been known since the early sixteenth century. Contact with its milky sap (latex) produces bullous dermatitis and acute keratoconjunctivitis. We identified 19 patients who had ocular injuries caused by Manchineel between 1985 and 1990 and were able to review 12. All of these patients had been treated by lavage, cycloplegia, and topical antibiotics. Of 20 episodes of exposure 14 affected both eyes. The cornea was damaged in 16 episodes, the extent varying from large corneal epithelial defects to superficial punctate keratitis. The epithelial changes had resolved in a mean period of 3.75 days (range 1 to 14 days). Two episodes caused stromal infiltration to appear and in one of these a stromal opacity remained 5 years later. The final visual acuity was 6/9 or better in all eyes except in one patient who had visual impairment because of glaucoma. Our results suggest that despite the severity of the acute reaction, the long term visual prognosis is excellent in Manchineel keratoconjunctivitis. The historical and toxicological literature on Manchineel is reviewed.