Mollicute-Like Organisms (MLO) have been reported to be a cause of uveal tract and orbital chronic inflammatory disease. MLO are intracellular cytopathogenic cell wall deficient bacteria. No culture system exists for MLO, MLO disease diagnosis is based chiefly on direct detection of the organisms within diseased cells using a transmission electron microscope. Uveitis producing MLO are detectable within vitreous leucocytes as 0.005-0.01 micron filaments and undulating pleomorphic 0.01-1.0 micron tubulo-spherical bodies. Human uveitis producing MLO can be passed to laboratory animals. Inoculation into mouse eyelids produced intraocular, orbital, and lethal systemic chronic progressive inflammatory disease. MLO parasitised lesional leucocytes were found in all the disease sites. The MLO induced mouse chronic interstitial pneumonitis displayed 'sarcoid-like' granulomas. This report describes MLO parasitised vitreous leucocytes in the chronic uveitis of four sarcoidosis patients. The results indicate that MLO caused the uveitis. The implications of the results and Rifampin treatment of MLO disease are discussed.