Bilateral conjunctivitis and episcleritis were identified in an adult European starling (Sturnus vulgaris). A novel mycoplasma species, Mycoplasma sturni, was isolated in pure culture from the conjunctiva of both eyes. The clinical presentation was similar to that of conjunctivitis in house finches (Carpodacus mexicanus) caused by Mycoplasma gallisepticum. However, the histologic lesions were distinct, by the presence of ulceration and epithelial hyperplasia and lacking a lymphoplasmacytic infiltration. Mycoplasma sturni ferments glucose, does not hemadsorb or hemagglutinate chicken erythrocytes, and grows rapidly at 37 C in comparison to other Mycoplasma spp. The role of M. sturni in conjunctivitis in other passerine species is presently unknown.