Purpose:To investigate the retinal toxicity of FK506 by intravitreal administration.Methods :Twenty-two eyes of 14 New Zealand rabbits were investigated. FK506 at con centrations of 5,25 and 50μg/eye was injected into the vitreous cavitiesrespectively.The control eyes were received mixed solution of balanced salt and ethanol. All eyes were examined by tonometry, slit lamp and indirect ophthalmoscopy preoperatively and post operatively at the 1st, 3rd, 7th, and 14th day respectively. In the final examination, all eyes were enucleated and processed for light and electron microscopy. Conclusion: It is safety with intravitreal FK506. There are no irritation and toxicity to the are proved to be toxic to the retina. Eye Science 2004;20:34-38.