Cidofovir, a nucleotide analogue virostatic drug is effective in the treatment of herpes virus infections. However, cytomegaly infection is the prime indication due to its adverse effects. There is growing evidence suggesting cidofovir's effectiveness against progressive multifocal leukoencephalopathy (PML) caused by a reactivation of JC-virus. Chronic ocular hypotension which seems to be therapy refractory and anterior uveitis are considered to be the most serious ocular complications of cidofovir. Secondary side effects such as macular folds, retinal or choroidal detachment can result in a permanent loss of vision. Little is known about the pathology of reduced intraocular pressure and only few reports deal with therapeutical attempts to compensate this complication. Abandoning cidofovir presently remains the only therapeutic option. To avoid serious damage it is of utmost importance to monitor all patients undergoing cidofovir administration for signs of anterior uveitis and ocular hypotension.