Properly designed and instituted sanitation will improve milk quality and reduce mastitis. The majority of mammary infections occur during milking. Since the populations of pathogenic organisms on the teat are directly correlated to the incidence of udder infections, hygienic practices in the milking parlor are of major importance to accomplish effective mastitis control. The organisms causing mastitis have two general sources. The contagious pathogens originating from infected udders are passed from cow to cow. The environmental agents are ubiquitous, gaining entrance to the mammary gland from external sources; they do not rely on intramammary infection for survival in the dairy environment. Cow hygiene in the milking parlor consists of three separate steps: premilking cleansing, sanitation of the milking unit between cows, and covering the teats with a germicide after milking. Each step has separate requirements in terms of product selection, concentration of germicide, time commitment, and mechanical assistance. Premilking sanitation is most effective against coliform-like infections as well as the other environmentals. Unit flushing and teat dipping are the greater deterrents to infection from the contagious pathogens, Staphylococcus aureus, Streptococcus agalactiae, and the Mycoplasma species. Extra care needs to be given to hygiene measures when infusing the mammary gland with antibiotics. Dipping the teats in an effective germicide both before and after infusion is highly effective in reducing mammary infections. Fresh cows and sick cows are both highly susceptible to infection. Only minimal sanitation of these animals while milking is generally practiced. Dipping prior to milking and leaving the germicide in contact with the teat while milking can be recommended as an additional procedure to reduce pathogens. All products used during milking should bear the label for product safety in food environments, and judicious use should not threaten product safety through potential residues.