Technical advice provided to the farmers to improve the udder health situation of their herd is not always efficient. The compliance with the control plan is quite low (Green et al., 2007). It could be partially due to the difficulty for the farmer to perceive the economic impact of such diseases and therefore also the cost-effectiveness of a new control plan. The aim of this study is to assess the effectiveness of an economic based approach to induce acceptance of the control plan by the farmers. The advisor's intervention for mastitis control consisted in a classical technical analysis and a diagnosis of the origin of mastitis followed by a discussion of a new control with technical and economic arguments with the farmer. Software was used to provide an economic estimation of mastitis problems on the farm based on annual incidence and severity of the disease and farm characteristics. Both initial (over 12 month before the intervention) and expected (over 12 month after the implementation of the plan) economic impact were estimated. It included the costs related to treatments and prevention measures, and the estimated loss of gross margin due to reduced milk yield, impaired longevity and diminished milk price. The approach was tested in 30 farms by 6 advisors (veterinary practitioners and specialized engineers) and was found relevant, operational and efficient by the farmers and advisers. A high level in compliance with the control plan by the farmer was obtained by this economic estimation taking into account the specificities of their farms. The new downloadable free software can now be used on the computer of every interested advisor or farmer in France