An examination of the economic impacts of reduced milk production associated with Johneʼs disease on Johneʼs-positive and Johneʼs-negative dairy operations indicated that, if Johneʼs disease had not existed in US dairy cows in 1996, then the economic surplus of Johneʼs-negative operations would have been $600 million±$530 million lower, while the economic surplus of Johneʼs-positive operations would have been higher by $28 million±$79 million, which was not significantly different from zero. The data available for projecting changes in surplus were not sufficiently precise to allow an exact statement on whether Johneʼs-positive operations would have been better or worse off economically, in terms of the value received for producing more milk if they had not been affected by Johneʼs disease. The changes in producer surplus, based upon eliminating specific epidemiological risk factors for Johneʼs disease, were disaggregated between Johneʼs-positive dairy operations exposed to the risk factor and all other US dairy operations. Eliminating the risk factor of having any cows not born on the operation would have had a significant positive effect on the economic surplus of Johneʼs-positive operations that had any cows not born on the operation.