Seventy free-ranging koalas (Phascolarctos cinereus) from Magnetic Island (Queensland, Australia) underwent an ocular examination, blood collection and serological examination for Chlamydia psittaci antibodies, and an examination of their teeth and genitalia. In 12 koalas long-standing unilateral keratitis was noted and in another 10 animals long-standing bilateral keratitis was observed. All animals were seronegative for Chlamydia psittaci and apart from some nasal discharge and a variety of assorted medical findings there was no sign of chlamydial infection. These ocular findings probably represent a new disease of unknown etiology.