Keratoconjunctivitis outbreaks occur each summer in reindeer (Rangifer tarandus tarandus) herds in western Alaska, USA. This condition has not been well characterized nor has a definitive primary etiologic agent been identified. We evaluated the eyes of 660 calves near Nome, Alaska, between 29 June and 14 July 2005. Clinical signs of keratoconjunctivitis were observed in 26/660 calves (3.9%). Samples were collected from the conjunctival sac of both affected (n=22) and unaffected (n=24) animals for bacterial culture, enzyme-linked immunosorbent assay testing for Chlamydophila psittaci, and for polymerase chain reaction assays for Mycoplasma and Moraxella spp. No primary bacterial or viral etiologic agent(s) were isolated or identified. The cause of keratoconjunctivitis among reindeer calves was not determined, but it could involve an anaerobic bacteria, a difficult-to-isolate viral agent, stress associated with repeated handling, ocular foreign bodies, exposure to corral dust or arthropods, or a combination.