The effects on the adoption of recommended mastitis control practices were compared of an on-farm mastitis education program, the provision of educational materials only, and no intervention. Changes in herd production resulting from the adoption of control procedures were also estimated. Nine herds previously receiving regular reproductive health services were provided with a mastitis control education program designed specifically for them. The education program covered the major current recommendations for controlling endemic mastitis. A further nine herds continued to receive only the reproductive program, while 18 similar herds were sent mastitis control literature only. Farmer practices in mastitis control and knowledge were recorded and evaluated in both December 1981 and February 1984 using a mailed questionnaire sent to the above 36 and a further 168 herds near St. Paul in the same 11 countries. The success of the education program was evaluated by comparing the rates of adoption of recommended mastitis control procedures and the discontinuation of inappropriate procedures. Changes in farmer-perceived rewards to dairying resulting from the program were evaluated for the specifically educated farmers receiving the on-farm education program. The specific mastitis control education program in association with regular reproductive health visits significantly increased the adoption of recommended procedures over other strategies. Adoption of appropriate management changes was not significantly different between herds which received no additional information and herds receiving informative literature alone. The introduction of teat dipping as a control procedure to a herd was associated with a significant increase (P < 0.05) in milk production, while the introduction of dry period therapy produced a non-significant increase (0.1>P>0.05). Farmers' perceptions of their rewards from dairying were significantly improved as a result of receiving the integrated mastitis control education program. This was true for the four major rewards identified.