Serratia spp. are Gram-negative environmental mastitis pathogens that are commonly found in soil and plant matter, including feed. Additionally, teat disinfectants can become contaminated with these organisms on-farm. Serratia spp. are commonly resistant to chlorhexidine gluconate disinfectants, so herds experiencing problems with Serratia mastitis should choose an alternative active ingredient. Due to limited cure rates, emphasis needs to be placed on prevention of these infections rather than on treatment.