The appearance and prevalence of the face fly, Musca autumnalis DeGeer, is suspected as a contributing factor in the increase of infectious bovine keratitis (pinkeye) in cattle. Preliminary studies were initiated in Massachusetts to determine the potential role of the face fly in the transmission of this disease. The more significant findings are: (a) the bacterium Moraxella bovis (Hauduroy) may remain viable in the environs of the fly up to 3 days; (b) M. bovis was readily recovered from the exudate from infected eyes; (c) M. bovis was readily recovered from wings and legs of face flies up to 3 days after exposure to laboratory cultures; (d) the bacterium apparently is rapidly destroyed in the digestive tract of the face fly; and (e) M. bovis was recovered from laboratory-reared flics exposed to lacrimal exudates on infected cattle in the field. Since the fly is a persistent feeder around eyes of cattle, these findings are further evidence tending to incriminate the face fly as a potential carrier of M. bovis .