Risk factors in animal health are defined as those variables associated with a probability of a disease to occur. Bovine mastitis is a multifactorial disease in which the use of milking machines can influence its presentation by transmission of pathogenic organisms, which are able to affect the mammary's gland defense mechanisms and create negative flows (milk impaets). By using a transversal epidemiological study, the dynamic and static features of milking machines in 37 farms specialized in milk production, ofthe Sabana ofBogota and Ubate and Chiquinquira Valleys (Colombia) were studied. In these farms, bovine mastitis risk factors, related to operation of milking machines were determinated and quantified as follows: poor vacuum reserve in the machine, inadequate response ability of the regulator, inadequate level of vacuum at the tip of the teat, vacuum fluctuations outside the normal fix range, slipping of milking units above 10%, different forms of overmilking, overmanipulation ofthe milking units, and faults in equipment periodic maintenance. In this study it was determinated that the wrong operation of the milking machine is having an influence on the presentation of bovine mastitis.